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What changed in Alliant Energy's 10-K — 2024 vs 2025

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Paragraph-level year-over-year comparison of Alliant Energy's 2024 and 2025 10-K annual filings, covering the Business, Risk Factors, Legal Proceedings, Cybersecurity, MD&A and Market Risk sections. Every new, removed and edited paragraph is highlighted side-by-side so you can see exactly what management changed in the 2025 report.

+348 added−327 removedSource: 10-K (2026-02-20) vs 10-K (2025-02-21)

Top changes in Alliant Energy's 2025 10-K

348 paragraphs added · 327 removed · 259 edited across 8 sections

Item 1. Business

Business — how the company describes what it does

64 edited+10 added−12 removed85 unchanged
Biggest change(b) All or some of the renewable energy attributes associated with generation from these sources may be used in future years to comply with renewable energy standards or other regulatory requirements. 13 Table of C o ntents Electric Operating Information IPL WPL 2024 2023 2022 2024 2023 2022 Revenues (in millions): Residential $640 $641 $673 $596 $579 $560 Commercial 525 519 536 296 301 285 Industrial 497 501 538 455 467 427 Retail subtotal 1,662 1,661 1,747 1,347 1,347 1,272 Sales for resale: Wholesale 61 62 64 139 151 169 Bulk power and other (6) 11 13 92 60 98 Other 30 27 35 47 26 23 Total $1,747 $1,761 $1,859 $1,625 $1,584 $1,562 Sales (000s MWh): Residential 3,573 3,586 3,793 3,531 3,590 3,686 Commercial 3,974 3,988 4,049 2,330 2,341 2,387 Industrial 6,073 6,335 6,428 5,088 5,100 5,066 Retail subtotal 13,620 13,909 14,270 10,949 11,031 11,139 Sales for resale: Wholesale 750 766 771 2,033 2,093 2,095 Bulk power and other 1,138 1,465 1,401 4,482 3,265 2,333 Other 32 32 33 25 26 29 Total 15,540 16,172 16,475 17,489 16,415 15,596 Customers (End of Period): Retail 503,279 500,938 498,515 499,688 495,044 490,854 Other 881 878 867 2,034 2,036 2,036 Total 504,160 501,816 499,382 501,722 497,080 492,890 Other Selected Electric Data: Maximum summer peak hour demand (MW) 2,833 2,940 2,895 2,805 2,926 2,800 Maximum winter peak hour demand (MW) 2,359 2,294 2,449 2,034 1,946 2,046 Cooling degree days (a): Cedar Rapids, Iowa (IPL) (normal - 819) 890 974 908 N/A N/A N/A Madison, Wisconsin (WPL) (normal - 704) N/A N/A N/A 742 781 787 Sources of electric energy (000s MWh): Gas 5,965 6,636 4,625 7,918 8,128 6,813 Purchased power: Wind (b) 2,681 2,504 2,985 1,604 1,563 1,437 Other (b) 1,228 730 835 487 1,153 1,968 Wind (b) 4,347 4,257 4,991 1,193 1,153 1,433 Solar (b) 119 11 11 1,714 460 30 Coal 1,442 2,252 3,305 4,762 4,195 4,111 Other (b) — 1 2 201 185 196 Total 15,782 16,391 16,754 17,879 16,837 15,988 Revenue per KWh sold to retail customers (cents) $12.20 $11.94 $12.24 $12.30 $12.21 $11.42 (a) Cooling degree days are calculated using a simple average of the high and low temperatures each day compared to a 65 degree base.
Biggest change(b) All or some of the renewable energy attributes associated with generation from these sources may be used in future years to comply with renewable energy standards or other regulatory requirements. 13 Table of Contents Electric Operating Information IPL WPL 2025 2024 2023 2025 2024 2023 Revenues (in millions): Residential $661 $640 $641 $678 $596 $579 Commercial 609 525 519 323 296 301 Industrial 531 497 501 503 455 467 Retail subtotal 1,801 1,662 1,661 1,504 1,347 1,347 Sales for resale: Wholesale 39 61 62 145 139 151 Bulk power and other 28 (6) 11 136 92 60 Other 28 30 27 16 47 26 Total $1,896 $1,747 $1,761 $1,801 $1,625 $1,584 Sales (000s MWh): Residential 3,722 3,573 3,586 3,671 3,531 3,590 Commercial 4,095 3,974 3,988 2,397 2,330 2,341 Industrial 6,065 6,073 6,335 5,172 5,088 5,100 Retail subtotal 13,882 13,620 13,909 11,240 10,949 11,031 Sales for resale: Wholesale 481 750 766 2,084 2,033 2,093 Bulk power and other 1,777 1,138 1,465 3,609 4,482 3,265 Other 31 32 32 25 25 26 Total 16,171 15,540 16,172 16,958 17,489 16,415 Customers (End of Period): Retail 505,636 503,279 500,938 503,751 499,688 495,044 Other 865 881 878 2,034 2,034 2,036 Total 506,501 504,160 501,816 505,785 501,722 497,080 Other Selected Electric Data: Maximum summer peak hour demand (MW) 2,759 2,833 2,940 2,735 2,805 2,926 Maximum winter peak hour demand (MW) 2,433 2,359 2,294 2,042 2,034 1,946 Cooling degree days (a): Cedar Rapids, Iowa (IPL) (normal - 831) 1,054 890 974 N/A N/A N/A Madison, Wisconsin (WPL) (normal - 716) N/A N/A N/A 755 742 781 Sources of electric energy (000s MWh): Gas 5,707 5,965 6,636 6,733 7,918 8,128 Purchased power: Wind (b) 2,622 2,681 2,504 1,543 1,604 1,563 Other (b) 493 1,228 730 628 487 1,153 Wind (b) 4,249 4,347 4,257 1,121 1,193 1,153 Solar (b) 740 119 11 2,071 1,714 460 Coal 2,577 1,442 2,252 5,147 4,762 4,195 Other (b) 1 — 1 190 201 185 Total 16,389 15,782 16,391 17,433 17,879 16,837 Revenue per KWh sold to retail customers (cents) $12.97 $12.20 $11.94 $13.38 $12.30 $12.21 (a) Cooling degree days are calculated using a simple average of the high and low temperatures each day compared to a 65 degree base.
WPL must obtain a CPCN from the PSCW in order to construct a new EGU (including energy storage) in Wisconsin with a capacity of 100 MW or more. In addition, WPL’s ownership and operation of EGUs (including those located outside the state of Wisconsin) to serve Wisconsin customers are subject to retail utility rate regulation by the PSCW.
WPL must obtain a CPCN from the PSCW in order to construct a new EGU or energy storage in Wisconsin with a capacity of 100 MW or more. In addition, WPL’s ownership and operation of EGUs (including those located outside the state of Wisconsin) to serve Wisconsin customers are subject to retail utility rate regulation by the PSCW.
Coal contracts entered into with different entities help ensure that a specified supply of coal is available, and delivered, at known prices for IPL’s and WPL’s coal-fired EGUs.
Coal - Coal contracts entered into with different entities help ensure that a specified supply of coal is available, and delivered, at known prices for IPL’s and WPL’s coal-fired EGUs.
Normal degree days are calculated using a rolling 20-year average of historical cooling degree days. Refer to “ Gas Operating Information ” below for details of heating degree days.
Normal degree days are calculated using a rolling 20-year average of historical cooling degree days. Refer to “ Gas Operating Information ” below for details of heating degree days.
Although electric service in Iowa and Wisconsin is regulated, IPL and WPL still face competition from self-generation by large industrial customers, customer- and third party-owned generation (e.g. solar panels), alternative energy sources, and petitions to municipalize (Iowa) as well as service territory expansions by municipal utilities through annexations (Wisconsin).
Although electric service in Iowa and Wisconsin is regulated, IPL and WPL face competition from self-generation by large industrial customers, customer- and third party-owned generation (e.g. solar panels), alternative energy sources, and petitions to municipalize (Iowa) as well as service territory expansions by municipal utilities through annexations (Wisconsin).
Alliant Energy’s strategy includes actions to retain current customers and attract new customers into IPL’s and WPL’s service territories in an effort to keep energy rates low for all of their customers. Refer to “ Overview ” in MDA for discussion of the strategy element focusing on growing customer demand.
Alliant Energy’s strategy includes actions to retain current customers and attract new customers into IPL’s and WPL’s service territories in an effort to keep energy rates low for all customers. Refer to “ Overview ” in MDA for discussion of the strategy element focusing on growing customer demand.
New Electric Generating Units - A CA application is required to be filed with the PSCW for construction approval of any new EGU (including energy storage) with a capacity of less than 100 MW and a project cost of $16.3 million or more.
New Electric Generating Units - A CA application is required to be filed with the PSCW for construction approval of any new EGU or energy storage with a capacity of less than 100 MW and a project cost of $16.3 million or more.
Electric Supply - Alliant Energy, IPL and WPL have met, and expect to continue meeting, customer demand of electricity through a mix of electric supply, including owned EGUs, PPAs and additional purchases from wholesale energy markets.
Electric Supply - Alliant Energy, IPL and WPL have met, and expect to continue meeting, customer demand for electricity through a mix of electric supply, including owned EGUs, PPAs and additional purchases from wholesale energy markets.
In 2009, the EPA issued a ruling that found GHG emissions contribute to climate change and therefore threaten public health and welfare, which is the basis for implementing CO2 reduction standards under the CAA. The primary GHG directly emitted from Alliant Energy’s utility operations is CO2 from the combustion of fossil fuels at its EGUs.
In 2009, the EPA issued a ruling that found GHG emissions from motor vehicles contribute to climate change and therefore threaten public health and welfare, which is the basis for implementing CO2 reduction standards under the CAA. The primary GHG directly emitted from Alliant Energy’s utility operations is CO2 from the combustion of fossil fuels at its EGUs.
Midwest Reliability Organization, which is a regional member of North American Electric Reliability Corporation, has direct responsibility for mandatory electric reliability standards for IPL and WPL.
The Midwest Reliability Organization, which is a regional member of North American Electric Reliability Corporation, has direct responsibility for mandatory electric reliability standards for IPL and WPL.
INFORMATION RELATING TO UTILITY OPERATIONS Alliant Energy’s utility business includes the operations of IPL (electric, gas and steam operations) and WPL (electric and gas operations), which are both reportable segments.
INFORMATION RELATING TO UTILITY OPERATIONS Alliant Energy’s utility business (electric and gas) includes the operations of IPL and WPL, which are both reportable segments.
Alliant Energy expects its current mix of electric supply to continue to evolve with new wind and solar generation, energy storage facilities, new natural gas resources, refurbishing of existing wind farms, improvements at existing natural gas-fired EGUs and converting certain coal-fired EGUs to natural gas.
Alliant Energy expects its current mix of electric supply to continue to evolve with new renewable generation, energy storage facilities, new natural gas resources, refurbishing of existing wind farms, improvements at existing natural gas-fired EGUs and converting certain coal-fired EGUs to natural gas.
Development goals and conversations with leadership help identify opportunities to learn through a mix of on-the-job experience, collaboration and formal content to build needed skills for today and the future. To help attract and introduce a wide range of candidates to our industry, we have early careers programs that include apprenticeships, youth programs (high school) and internships (college).
Development goals and conversations with leadership help identify opportunities to learn through a mix of on-the-job experience, collaboration and formal content to build needed skills for today and the future. To help attract and introduce a wide range of candidates to our industry, we have early careers programs that include youth programs (high school), pre-apprenticeships, and apprenticeships.
In addition, Alliant Energy is subject to regulation by the PSCW for the type and amount of Alliant Energy’s holdings in non-utility businesses and other affiliated interest activities, among other matters. Retail Utility Base Rates - WPL files periodic requests with the PSCW for retail rate changes, which are based on forward-looking test periods.
In addition, Alliant Energy is subject to regulation by the PSCW for the type and amount of Alliant Energy’s holdings in non-utility businesses and other affiliated interest activities, among other matters. 7 Table of Contents Retail Utility Base Rates - WPL files periodic requests with the PSCW for retail rate changes, which are based on forward-looking test periods.
Clean Air Act Section 111(d) - In May 2024, the EPA enacted the final Section 111(d) rule under the CAA for certain fossil-fueled EGUs, which requires states to implement plans to reduce CO2 emissions through various Best System of Emission Reduction (BSER) measures at affected sources, including retirement, enforceable limits on operational capacity, co-firing with low-GHG fuels, or carbon capture and energy storage technology.
Cl ean Air Act Section 111(d) - In May 2024, the EPA enacted the final Section 111(d) rule under the CAA for certain fossil-fueled EGUs, which requires states to implement plans to reduce CO2 emissions through various Best System of Emission Reduction (BSER) measures at affected sources, including retirement, enforceable limits on operational capacity, co-firing with low-GHG fuels, or carbon capture and storage technology.
IPL and WPL utilize accredited capacity from EGUs they own, and have rights to through PPAs, to meet a substantial portion of their current MISO planning reserve margin requirements and periodically rely on short-term market capacity purchases to supplement the accredited capacity from such EGUs. 10 Table of C o ntents MISO Seasonal Resource Adequacy Process - MISO’s resource adequacy process includes capacity planning reserve margins and capacity accreditation requirements with four distinct seasons, to help ensure the reliability of electricity in the MISO region.
IPL and WPL utilize accredited capacity from EGUs they own, and have rights to through PPAs, to meet a substantial portion of their current MISO planning reserve margin requirements and periodically rely on short-term market capacity purchases to supplement the accredited capacity from such EGUs. 10 Table of Contents MISO Seasonal Resource Adequacy Process - MISO’s resource adequacy process includes capacity planning reserve margins and capacity accreditation requirements with four distinct seasons, to help ensure the reliability of electricity in the MISO region.
Refer to the “ Gas Operating Information ” tables for additional details regarding gas utility operations. Refer to Note 1(g) for information relating to utility natural gas cost recovery mechanisms and Note 1 6 (b) for discussion of natural gas commitments.
Refer to the “ Gas Operating Information ” tables for additional details regarding gas utility operations. Refer to Not e 1(g) for information relating to utility natural gas cost recovery mechanisms and Note 1 6 (b) for discussion of natural gas commitments.
Refer to Note 1(g) for discussion of a transmission cost rider utilized by IPL for recovery of its electric transmission service expense, and discussion of WPL’s escrow for recovery of electric transmission service expense, which is recovered from its retail electric customers through changes in base rates determined during periodic rate proceedings.
Refer to N ote 1(g) for discussion of a transmission cost rider utilized by IPL for recovery of its electric transmission service expense, and discussion of WPL’s escrow for recovery of electric transmission service expense, which is recovered from its retail electric customers through changes in base rates determined during periodic rate proceedings.
Alliant Energy, IPL and WPL are currently unable to predict with certainty the future outcome or impact of these matters, including resolution of ongoing litigation. 8 Table of C o ntents Clean Air Act Section 111(b) - In 2015, the EPA published final standards under Section 111(b) of the CAA, which establish CO2 emissions limits for certain new fossil-fueled EGUs, including IPL’s Marshalltown Generation Station and WPL’s West Riverside Energy Center.
Alliant Energy, IPL and WPL are currently unable to predict with certainty the future outcome or impact of these matters, including resolution of ongoing or potential litigation. 8 Table of Contents Clean Air Act Section 111(b) - In 2015, the EPA published final standards under Section 111(b) of the CAA, which establish CO2 emissions limits for certain new fossil-fueled EGUs, including IPL’s Marshalltown Generation Station and WPL’s West Riverside Energy Center.
IPL provides utility services to incorporated communities as directed by the IUC and utilizes non-exclusive franchises, which cover the use of public right-of-ways for utility facilities in incorporated communities for a maximum term of 25 years. At December 31, 2024, IPL supplied electric and natural gas service to approximately 500,000 and 230,000 retail customers, respectively, in Iowa.
IPL provides utility services to incorporated communities as directed by the IUC and utilizes non-exclusive franchises, which cover the use of public right-of-ways for utility facilities in incorporated communities for a maximum term of 25 years. At December 31, 2025, IPL supplied electric and natural gas service to approximately 505,000 and 230,000 retail customers, respectively, in Iowa.
Competition - Retail electric customers in Iowa and Wisconsin currently do not have the ability to choose their electric supplier, and IPL and WPL have obligations to serve all their retail electric customers.
Competition - Retail electric customers in Iowa and Wisconsin currently do not have the ability to choose their electric supplier, and IPL and WPL have obligations to serve all retail electric customers in their service territories.
(b) All or some of the renewable energy attributes associated with generation from these sources may be used in future years to comply with renewable energy standards or other regulatory requirements. 14 Table of C o ntents 2) GAS UTILITY OPERATIONS General - Alliant Energy’s gas utility operations are located in the Midwest with IPL providing gas service in Iowa and WPL providing gas service in Wisconsin.
(b) All or some of the renewable energy attributes associated with generation from these sources may be used in future years to comply with renewable energy standards or other regulatory requirements. 14 Table of Contents 2) GAS UTILITY OPERATIONS General - Alliant Energy’s gas utility operations are located in the Midwest with IPL providing gas service in Iowa and WPL providing gas service in Wisconsin.
In addition to competitive salaries and wages, our Total Rewards programs include: • competitive short- and long-term incentive compensation; • a 401(k) savings plan with an employer contribution and employer match; • healthcare and insurance benefits, including medical, vision, dental, life, short-term disability, and long-term disability insurance; • health savings and flexible spending accounts; • enhanced offerings to support the well-being of employees and their families; • paid time off to use for vacation, personal time, sick time, holidays, bereavement, jury duty, military leave, parental leave, maternity leave, and adoption leave; • adoption assistance; • legal planning assistance; • tuition reimbursement; • Vacation Donation program; and • Volunteer Grants and a Matching Gifts program.
In addition to competitive salaries and wages, our Total Rewards programs include: • competitive short- and long-term incentive compensation that align employees with strategic corporate goals; • a 401(k) savings plan with an employer contribution and employer match; • healthcare and insurance benefits, including medical, vision, dental, mental health resources, life, short-term disability, and long-term disability insurance; • health savings and flexible spending accounts; • enhanced offerings to support the well-being of employees and their families; • paid time off to use for vacation, personal time, sick time, holidays, bereavement, jury duty, military leave, parental leave, maternity leave, and adoption leave; • adoption assistance; • legal planning assistance; • tuition reimbursement; • Vacation Donation program; and • Volunteer Grants and a Matching Gifts program.
Development-ready Sites - includes various rail-served and ready-to-build manufacturing and industrial sites throughout Alliant Energy’s service territories, with access to various airports and interstate freeways. B. INFORMATION RELATING TO ALLIANT ENERGY ON A CONSOLIDATED BASIS 1) HUMAN CAPITAL MANAGEMENT - Alliant Energy’s core purpose is to serve customers and build stronger communities.
Development-ready Sites - includes various rail-served and ready-to-build manufacturing and industrial sites throughout Alliant Energy’s service territories, with access to various airports and interstate freeways. 4 Table of Contents B. INFORMATION RELATING TO ALLIANT ENERGY ON A CONSOLIDATED BASIS 1) HUMAN CAPITAL MANAGEMENT - Alliant Energy’s core purpose is to serve customers and build stronger communities.
Customers - IPL and WPL provide electric utility service to a large base of retail customers in several industries, with the largest concentrations in the farming, agriculture, industrial manufacturing, chemical (including ethanol), packaging and food industries. IPL and WPL also sell electricity to wholesale customers, which primarily consist of municipalities and rural electric cooperatives.
Customers - IPL and WPL provide electric utility service to a large base of retail customers in several industries, with the largest concentrations in the farming, agriculture, industrial manufacturing, chemical (including ethanol), pipeline transportation, packaging and food industries, and data centers. IPL and WPL also sell electricity to wholesale customers, which primarily consist of municipalities and rural electric cooperatives.
Purchased Power - IPL and WPL periodically enter into PPAs and purchase electricity from wholesale energy markets to meet a portion of their customer demand for electricity. 11 Table of C o ntents Electric Transmission - IPL and WPL do not own electric transmission service assets and currently receive transmission services from ITC and ATC, respectively.
Purchased Power - IPL and WPL periodically enter into PPAs and purchase electricity from wholesale energy markets to meet a portion of their customer demand for electricity. 11 Table of Contents Electric Transmission - IPL and WPL do not own electric transmission service assets and currently receive transmission services from ITC and ATC, respectively.
In Iowa, counties and cities are prohibited from regulating the sale of natural gas and propane, which supports IPL’s ability to provide gas utility service to retail customers and industries. 6 Table of C o ntents Retail Utility Base Rates - IPL files periodic requests with the IUC for retail rate changes and may base those requests on either historical or forward-looking test periods.
In Iowa, counties and cities are prohibited from regulating the sale of natural gas and propane, which supports IPL’s ability to provide gas utility service to retail customers and industries. Retail Utility Base Rates - IPL files periodic requests with the IUC for retail rate changes and may base those requests on either historical or forward-looking test periods.
Alliant Energy’s primary focus is to provide regulated electric and natural gas service to approximately 1,000,000 electric and approximately 430,000 natural gas customers in the Midwest through its two public utility subsidiaries, IPL and WPL.
Alliant Energy’s primary focus is to provide regulated electric and natural gas service to approximately 1,010,000 electric and approximately 435,000 natural gas customers in the Midwest through its two public utility subsidiaries, IPL and WPL.
Gas Demand Planning Reserve Margin - IPL and WPL are required to maintain adequate pipeline capacity to ensure they meet their customers’ maximum daily system demand requirements. IPL and WPL currently have planning reserve margins of 2% and 5%, respectively, above their forecasted maximum daily system demand requirements from November 2024 through March 2025.
Gas Demand Planning Reserve Margin - IPL and WPL are required to maintain adequate pipeline capacity to ensure they meet their customers’ maximum daily system demand requirements. IPL and WPL currently have planning reserve margins of 2% and 1%, respectively, above their forecasted maximum daily system demand requirements from November 2025 through March 2026.
IPL and WPL currently exceed their respective renewable energy standards requirements. 3) STRATEGY - Refer to “ Overview ” in MDA for discussion of Alliant Energy’s strategy, which supports its mission to deliver energy solutions and exceptional service that its customers and communities count on - affordably, safely, reliably and sustainably. 9 Table of C o ntents C.
IPL and WPL currently exceed their respective renewable energy standards requirements. 3) STRATEGY - Refer to “ Overview ” in MDA for discussion of Alliant Energy’s strategy, which supports its mission to deliver energy solutions and exceptional service that its customers and communities count on - affordably, safely, reliably and responsibly. 9 Table of Contents C.
Currently, WPL is required to defer a portion of its earnings if its annual regulatory return on common equity exceeds certain levels. 7 Table of C o ntents Public Benefits - WPL contributes 1.2% of its annual retail utility revenues to help fund Focus on Energy, Wisconsin’s state-wide energy efficiency and renewable energy resource program.
Currently, WPL is required to defer a portion of its earnings if its annual regulatory return on common equity exceeds certain levels. Public Benefits - WPL contributes 1.2% of its annual retail utility revenues to help fund Focus on Energy, Wisconsin’s state-wide energy efficiency and renewable energy resource program.
WPL can proceed with an approved project under traditional rate-making terms or accept authorized rate-making principles under Wisconsin law. Department of Homeland Security Transportation Security Administration - Alliant Energy, IPL and WPL are subject to regulation for physical and cybersecurity of their natural gas pipeline systems, and are applying, and monitoring for changes to, these requirements to their pipeline systems.
WPL can proceed with an approved project under traditional rate-making terms or accept authorized rate-making principles under Wisconsin law. Department of Homeland Security Transportation Security Administration - Alliant Energy, IPL and WPL are subject to regulation for physical and cybersecurity of their natural gas pipeline systems.
All of WPL’s bargaining unit employees are covered by the International Brotherhood of Electrical Workers Local 965 collective bargaining agreement, which expires May 31, 2026. 4 Table of C o ntents Safety - Safety is integral to our company’s culture. It is one of our Values - “Live safety. Everyone. Always.
All of WPL’s bargaining unit employees are covered by the International Brotherhood of Electrical Workers Local 965 collective bargaining agreement, which expires May 31, 2026. Safety - Safety is integral to our company’s culture. It is one of our Values - “Live safety. Everyone. Always.
The primary first tier wholly-owned subsidiaries of Alliant Energy are as follows: 3 Table of C o ntents 1) IPL - is a public utility engaged principally in the generation and distribution of electricity and the distribution and transportation of natural gas to retail customers in select markets in Iowa.
The primary first tier wholly-owned subsidiaries of Alliant Energy are as follows: 1) IPL - is a public utility engaged principally in the generation and distribution of electricity and the distribution and transportation of natural gas to retail customers in select markets in Iowa.
Travero - is a supply chain solutions company, including a short-line rail freight service in Iowa; a Mississippi River barge, rail and truck freight terminal in Illinois; freight brokerage services; wind turbine blade recycling services; and a rail-served warehouse in Iowa.
Travero - is a supply chain solutions company, including a short-line rail freight service in Iowa; a Mississippi River barge, rail and truck freight terminal in Illinois; freight brokerage services; and a rail-served warehouse in Iowa.
Alliant Energy, IPL and WPL currently plan to construct and/or acquire additional renewable, energy storage and natural gas resources to meet the requirements of the seasonal resource adequacy process and have reflected the estimated capital expenditures for these projects in the “Generation” lines in the construction and acquisition table in “ Liquidity and Capital Resources .” Seasonal capacity reserve margins are as follows: June 2025 - August 2025 September 2025 - November 2025 December 2025 - February 2026 March 2026 - May 2026 Required installed capacity reserve margin 15.7% 25.3% 38.6% 38.8% Required unforced capacity reserve margin 7.9% 14.9% 18.4% 25.3% Generation Fuel Supply - IPL and WPL own a portfolio of EGUs located in Iowa, Wisconsin and Minnesota with a fuel mix that includes natural gas, renewable resources and coal.
Alliant Energy, IPL and WPL currently plan to construct and/or acquire additional renewable, energy storage and natural gas resources to meet the requirements of the seasonal resource adequacy process and have reflected the estimated capital expenditures for these projects in the “Generation” lines in the construction and acquisition table in “ Liquidity and Capital Resources .” Seasonal capacity reserve margins are as follows: June 2026 - August 2026 September 2026 - November 2026 December 2026 - February 2027 March 2027 - May 2027 Required installed capacity reserve margin 15.0% 22.1% 42.2% 42.0% Required unforced capacity reserve margin 7.9% 11.6% 18.9% 23.4% Generation Fuel Supply - IPL and WPL own a portfolio of EGUs located in Iowa, Wisconsin and Minnesota with a fuel mix that includes natural gas, renewable resources and coal.
WPL operates in municipalities pursuant to permits of indefinite duration and state statutes authorizing utility operation in areas annexed by a municipality. At December 31, 2024, WPL supplied electric and natural gas service to approximately 500,000 and 200,000 retail customers, respectively.
WPL operates in municipalities pursuant to permits of indefinite duration and state statutes authorizing utility operation in areas annexed by a municipality. At December 31, 2025, WPL supplied electric and natural gas service to approximately 505,000 and 205,000 retail customers, respectively.
Alliant Energy, IPL and WPL believe they are reasonably insulated against gas price volatility for these EGUs given their use of forward contracts and hedging practices, as well as their regulatory cost-recovery mechanisms. Coal - Coal is one of the fuel sources for owned EGUs.
Alliant Energy, IPL and WPL believe they are reasonably insulated against gas price volatility for these EGUs given their use of forward contracts and hedging practices, as well as their regulatory cost-recovery mechanisms.
The average cost of delivered fuel per million British Thermal Units used for electric generation was as follows: IPL WPL 2024 2023 2022 2024 2023 2022 All fuels $2.49 $2.83 $4.37 $2.74 $3.09 $4.47 Natural gas (a) 2.52 3.10 5.76 3.03 3.47 6.02 Coal 2.29 2.09 2.31 2.37 2.54 2.43 (a) The average cost of natural gas includes commodity and transportation costs, as well as realized gains and losses from swap and option contracts used to hedge the price of natural gas volumes expected to be used by IPL’s and WPL’s natural gas-fired EGUs.
The average cost of delivered fuel per million British Thermal Units used for electric generation was as follows: IPL WPL 2025 2024 2023 2025 2024 2023 All fuels $2.81 $2.49 $2.83 $3.11 $2.74 $3.09 Natural gas (a) 3.05 2.52 3.10 3.84 3.03 3.47 Coal 2.28 2.29 2.09 2.41 2.37 2.54 (a) The average cost of natural gas includes commodity and transportation costs, as well as realized gains and losses from swap and option contracts used to hedge the price of natural gas volumes expected to be used by IPL’s and WPL’s natural gas-fired EGUs.
Total Rewards - Our market-competitive Total Rewards programs are designed to meet the varied and evolving needs of our employees. Through a variety of health, welfare and compensation programs, we offer employees choice and control, and help support their financial, physical, and mental well-being. We provide tools and resources to employees to help maintain and improve their health.
Total Rewards - Our market-competitive Total Rewards programs are designed to meet the varied and evolving needs of our employees. Through a variety of programs, we offer employees choice and control, and help support their financial, physical, and mental well-being.
The final rule’s compliance requirements will be phased in beginning in 2030 and covers fossil-fueled EGUs that utilize steam boilers to generate electricity, including IPL’s coal-fired Ottumwa Generating Station, George Neal Generating Station, Prairie Creek Generating Station Unit 3 and Louisa Generating Station, WPL’s coal-fired Edgewater Generating Station Unit 5 (WPL currently plans to convert Edgewater Unit 5 to natural gas in 2028, subject to regulatory approvals), and IPL’s natural gas-fired Burlington Generating Station and Prairie Creek Generating Station Unit 4.
The final rule’s compliance requirements will be phased in beginning in 2030 and covers fossil-fueled EGUs that utilize steam boilers to generate electricity, including IPL’s coal-fired Ottumwa Generating Station, George Neal Generating Station, and Louisa Generating Station, WPL’s coal-fired Edgewater Generating Station Unit 5 and Columbia Units 1 and 2, and IPL’s natural gas-fired Burlington Generating Station and Prairie Creek Generating Station Units 3 and 4.
IPL and WPL do not own or operate FERC-regulated electric transmission facilities; however, both IPL and WPL pay for the use of the interstate electric transmission system based upon FERC-regulated rates. IPL and WPL rely primarily on the use of the ITC and ATC transmission systems, respectively.
IPL and WPL do not own or operate FERC-regulated electric transmission facilities; however, both IPL and WPL pay for the use of the interstate electric transmission system based upon FERC-regulated rates.
IUC approval demonstrates that IPL’s EEP is reasonably expected to achieve cost-effective delivery of the energy efficiency programs. Refer to Note 1(g) for discussion of the recovery of these costs from IPL’s retail electric and gas customers.
An EEP provides a utility’s plan and related budget to achieve specified levels of electric and gas energy savings. IUC approval demonstrates that IPL’s EEP is reasonably expected to achieve cost-effective delivery of the energy efficiency programs. Refer to Note 1(g) for discussion of the recovery of these costs from IPL’s retail electric and gas customers.
Employees - At December 31, 2024, Alliant Energy, IPL and WPL had the following full- and part-time employees: Total Number of Percentage of Employees Number of Bargaining Unit Covered by Collective Employees Employees Bargaining Agreements Alliant Energy 2,998 1,732 58% IPL 1,043 759 73% WPL 1,003 860 86% The majority of IPL’s bargaining unit employees are covered by the International Brotherhood of Electrical Workers Local 204 (Cedar Rapids) collective bargaining agreement, which expires August 31, 2028.
Employees - At December 31, 2025, Alliant Energy, IPL and WPL had the following full- and part-time employees: Total Number of Percentage of Employees Number of Bargaining Unit Covered by Collective Employees Employees Bargaining Agreements Alliant Energy 2,948 1,705 58% IPL 1,003 739 74% WPL 992 853 86% The majority of IPL’s bargaining unit employees are covered by the International Brotherhood of Electrical Workers Local 204 (Cedar Rapids) collective bargaining agreement, which expires August 31, 2028.
Water Quality - Effluent Limitation Guidelines - In May 2024, the EPA enacted a final rule that revises discharge limits for specific categories of wastewater from existing steam EGUs. The new limitations will be implemented in each facility’s wastewater discharge permits issued by state agencies and become effective as soon as possible but no later than December 31, 2029.
Water Quality - Effluent Limitation Guidelines - In May 2024, the EPA enacted a final rule that revises discharge limits for specific categories of wastewater from existing steam EGUs. The new limitations will be implemented in each facility’s wastewater discharge permits issued by state agencies.
Our efforts to advance employee engagement in our workforce include: • Learning: We offer various learning opportunities for employees, such as participating in area summits, supporting company-wide listening sessions, providing training opportunities, and hosting speakers, among other programs, as well as leaders facilitating conversations around employee engagement, helping to ensure employees are seen, heard and valued; • Listening and responding: We collect and act upon feedback through employee sentiment surveys; • Empowering: We promote and foster an engaged workforce, providing opportunities to collaborate, network, and share their insights and talents; and • Leading: Our Leadership Team identifies and champions initiatives to help advance a culture that values employee engagement. 5 Table of C o ntents Talent Development and Workforce Readiness - We support all employees in their skill development and career growth, offering several training opportunities, development programs and tuition reimbursement, as well as leadership development and succession planning.
Our efforts to advance employee engagement in our workforce include: • Learning: We offer various learning opportunities for employees, such as participating in area summits, supporting and engaging with company-wide Communities of Purpose, providing training opportunities, and hosting speakers where employees can ask questions and interact with business leaders and other experts, among other programs, as well as leaders facilitating conversations around employee engagement, helping to ensure employees are seen, heard and valued; • Listening and responding: We collect and act upon feedback through employee sentiment surveys; • Empowering: We promote and foster an engaged workforce, providing opportunities to collaborate, network, and share their insights and talents; and • Leading: Our Leadership Team identifies and champions initiatives to help advance a culture that values employee engagement.
IPL primarily relies upon renewable energy generated from the wind or solar resources it owns and renewable energy acquired under PPAs to meet these requirements. WPL utilizes its current renewable portfolio, which primarily consists of wind, solar and hydro energy, both owned and acquired under PPAs, to meet these requirements.
WPL utilizes its current renewable portfolio, which primarily consists of wind, solar and hydro energy, both owned and acquired under PPAs, to meet these requirements.
Refer to “ Electric Demand Planning Reserve Margin ” above for discussion of MISO’s seasonal resource adequacy process establishing capacity planning reserve margin and capacity accreditation requirements. 12 Table of C o ntents Electric Operating Information - Alliant Energy 2024 2023 2022 Revenues (in millions): Residential $1,236 $1,220 $1,233 Commercial 821 820 821 Industrial 952 968 965 Retail subtotal 3,009 3,008 3,019 Sales for resale: Wholesale 200 213 233 Bulk power and other 86 71 111 Other 77 53 58 Total $3,372 $3,345 $3,421 Sales (000s MWh): Residential 7,104 7,176 7,479 Commercial 6,304 6,329 6,436 Industrial 11,161 11,435 11,494 Retail subtotal 24,569 24,940 25,409 Sales for resale: Wholesale 2,783 2,859 2,866 Bulk power and other 5,620 4,730 3,734 Other 57 58 62 Total 33,029 32,587 32,071 Customers (End of Period): Retail 1,002,967 995,982 989,369 Other 2,915 2,914 2,903 Total 1,005,882 998,896 992,272 Other Selected Electric Data: Maximum summer peak hour demand (MW) 5,638 5,856 5,629 Maximum winter peak hour demand (MW) 4,317 4,240 4,415 Cooling degree days (a): Cedar Rapids, Iowa (IPL) (normal - 819) 890 974 908 Madison, Wisconsin (WPL) (normal - 704) 742 781 787 Sources of electric energy (000s MWh): Gas 13,883 14,764 11,438 Purchased power: Wind (b) 4,285 4,067 4,422 Other (b) 1,715 1,883 2,803 Wind (b) 5,540 5,410 6,424 Solar (b) 1,833 471 41 Coal 6,204 6,447 7,416 Other (b) 201 186 198 Total 33,661 33,228 32,742 Revenue per KWh sold to retail customers (cents) $12.25 $12.06 $11.88 (a) Cooling degree days are calculated using a simple average of the high and low temperatures each day compared to a 65 degree base.
Refer to “ Electric Demand Planning Reserve Margi n ” above for discussion of MISO’s seasonal resource adequacy process establishing capacity planning reserve margin and capacity accreditation requirements. 12 Table of Contents Electric Operating Information - Alliant Energy 2025 2024 2023 Revenues (in millions): Residential $1,339 $1,236 $1,220 Commercial 932 821 820 Industrial 1,034 952 968 Retail subtotal 3,305 3,009 3,008 Sales for resale: Wholesale 184 200 213 Bulk power and other 164 86 71 Other 44 77 53 Total $3,697 $3,372 $3,345 Sales (000s MWh): Residential 7,393 7,104 7,176 Commercial 6,492 6,304 6,329 Industrial 11,237 11,161 11,435 Retail subtotal 25,122 24,569 24,940 Sales for resale: Wholesale 2,565 2,783 2,859 Bulk power and other 5,386 5,620 4,730 Other 56 57 58 Total 33,129 33,029 32,587 Customers (End of Period): Retail 1,009,387 1,002,967 995,982 Other 2,899 2,915 2,914 Total 1,012,286 1,005,882 998,896 Other Selected Electric Data: Maximum summer peak hour demand (MW) 5,465 5,638 5,856 Maximum winter peak hour demand (MW) 4,433 4,317 4,240 Cooling degree days (a): Cedar Rapids, Iowa (IPL) (normal - 831) 1,054 890 974 Madison, Wisconsin (WPL) (normal - 716) 755 742 781 Sources of electric energy (000s MWh): Gas 12,440 13,883 14,764 Purchased power: Wind (b) 4,165 4,285 4,067 Other (b) 1,121 1,715 1,883 Wind (b) 5,370 5,540 5,410 Solar (b) 2,811 1,833 471 Coal 7,724 6,204 6,447 Other (b) 191 201 186 Total 33,822 33,661 33,228 Revenue per KWh sold to retail customers (cents) $13.16 $12.25 $12.06 (a) Cooling degree days are calculated using a simple average of the high and low temperatures each day compared to a 65 degree base.
IPL also sells electricity to wholesale customers in Minnesota and Illinois. Refer to the “ Electric Operating Information ” tables for additional details regarding electric utility operations.
IPL also sells electricity to wholesale customers in Illinois. IPL’s wholesale power agreement with Southern Minnesota Energy Cooperative expired in 2025. Refer to the “ Electric Operating Information ” tables for additional details regarding electric utility operations.
Gas Operating Information - Alliant Energy 2024 2023 2022 Revenues (in millions): Residential $275 $316 $371 Commercial 133 163 197 Industrial 11 16 20 Retail subtotal 419 495 588 Transportation/other 46 45 54 Total $465 $540 $642 Sales (000s Dths): Residential 24,243 25,838 31,109 Commercial 16,974 18,291 21,097 Industrial 2,272 2,276 2,815 Retail subtotal 43,489 46,405 55,021 Transportation/other 123,386 115,177 104,812 Total 166,875 161,582 159,833 Retail Customers (End of Period) 430,699 428,143 426,153 Other Selected Gas Data: Heating degree days (a): Cedar Rapids, Iowa (IPL) (normal - 6,736) 5,450 5,807 7,222 Madison, Wisconsin (WPL) (normal - 6,987) 5,801 6,157 7,210 Revenue per Dth sold to retail customers $9.63 $10.67 $10.69 Purchased gas costs per Dth sold to retail customers $5.06 $6.37 $6.97 15 Table of C o ntents Gas Operating Information IPL WPL 2024 2023 2022 2024 2023 2022 Revenues (in millions): Residential $148 $176 $202 $127 $140 $169 Commercial 68 86 101 65 77 96 Industrial 7 11 14 4 5 6 Retail subtotal 223 273 317 196 222 271 Transportation/other 27 27 34 19 18 20 Total $250 $300 $351 $215 $240 $291 Sales (000s Dths): Residential 12,413 13,146 16,250 11,830 12,692 14,859 Commercial 7,714 8,477 10,257 9,260 9,814 10,840 Industrial 1,513 1,505 1,985 759 771 830 Retail subtotal 21,640 23,128 28,492 21,849 23,277 26,529 Transportation/other 43,075 43,232 43,264 80,311 71,945 61,548 Total 64,715 66,360 71,756 102,160 95,222 88,077 Retail Customers (End of Period) 226,838 226,265 226,284 203,861 201,878 199,869 Other Selected Gas Data: Maximum daily winter peak demand (Dth) 267,820 290,922 259,474 221,135 234,796 201,980 Heating degree days (a): Cedar Rapids, Iowa (IPL) (normal - 6,736) 5,450 5,807 7,222 N/A N/A N/A Madison, Wisconsin (WPL) (normal - 6,987) N/A N/A N/A 5,801 6,157 7,210 Revenue per Dth sold to retail customers $10.30 $11.80 $11.13 $8.97 $9.54 $10.22 Purchased gas cost per Dth sold to retail customers $5.68 $7.16 $7.17 $4.44 $5.59 $6.77 (a) Heating degree days are calculated using a simple average of the high and low temperatures each day compared to a 65 degree base.
Gas Operating Information - Alliant Energy 2025 2024 2023 Revenues (in millions): Residential $306 $275 $316 Commercial 153 133 163 Industrial 13 11 16 Retail subtotal 472 419 495 Transportation/other 53 46 45 Total $525 $465 $540 Sales (000s Dths): Residential 27,945 24,243 25,838 Commercial 19,264 16,974 18,291 Industrial 2,154 2,272 2,276 Retail subtotal 49,363 43,489 46,405 Transportation/other 123,141 123,386 115,177 Total 172,504 166,875 161,582 Retail Customers (End of Period) 433,344 430,699 428,143 Other Selected Gas Data: Heating degree days (a): Cedar Rapids, Iowa (IPL) (normal - 6,684) 6,215 5,450 5,807 Madison, Wisconsin (WPL) (normal - 6,929) 6,841 5,801 6,157 Revenue per Dth sold to retail customers $9.56 $9.63 $10.67 Purchased gas costs per Dth sold to retail customers $5.24 $5.06 $6.37 15 Table of Contents Gas Operating Information IPL WPL 2025 2024 2023 2025 2024 2023 Revenues (in millions): Residential $155 $148 $176 $151 $127 $140 Commercial 72 68 86 81 65 77 Industrial 7 7 11 6 4 5 Retail subtotal 234 223 273 238 196 222 Transportation/other 31 27 27 22 19 18 Total $265 $250 $300 $260 $215 $240 Sales (000s Dths): Residential 14,026 12,413 13,146 13,919 11,830 12,692 Commercial 8,427 7,714 8,477 10,837 9,260 9,814 Industrial 1,257 1,513 1,505 897 759 771 Retail subtotal 23,710 21,640 23,128 25,653 21,849 23,277 Transportation/other 44,489 43,075 43,232 78,652 80,311 71,945 Total 68,199 64,715 66,360 104,305 102,160 95,222 Retail Customers (End of Period) 227,345 226,838 226,265 205,999 203,861 201,878 Other Selected Gas Data: Maximum daily winter peak demand (Dth) 266,886 267,820 290,922 250,286 221,135 234,796 Heating degree days (a): Cedar Rapids, Iowa (IPL) (normal - 6,684) 6,215 5,450 5,807 N/A N/A N/A Madison, Wisconsin (WPL) (normal - 6,929) N/A N/A N/A 6,841 5,801 6,157 Revenue per Dth sold to retail customers $9.87 $10.30 $11.80 $9.28 $8.97 $9.54 Purchased gas cost per Dth sold to retail customers $5.51 $5.68 $7.16 $4.98 $4.44 $5.59 (a) Heating degree days are calculated using a simple average of the high and low temperatures each day compared to a 65 degree base.
Natural Gas Act - FERC regulates the transportation and sale for resale of natural gas in interstate commerce under the Natural Gas Act. Under the Natural Gas Act, FERC has authority over certain natural gas facilities and operations of IPL and WPL.
Under the Natural Gas Act, FERC has authority over certain natural gas facilities and operations of IPL and WPL.
ATC Holdings is comprised of a 16% ownership interest in ATC and a 20% ownership interest in ATC Holdco LLC. ATC is an independent, for-profit, transmission-only company. ATC Holdco LLC holds an interest in Duke-American Transmission Company, LLC, a joint venture between Duke Energy Corporation and ATC, that owns electric transmission infrastructure in North America.
ATC Holdings is comprised of a 16% ownership interest in ATC and a 20% ownership interest in ATC Holdco LLC. ATC is an independent, for-profit, transmission-only company. ATC Holdco LLC holds an interest in Duke-American Transmission Company, LLC, which holds a note receivable related to the previously owned electric transmission infrastructure in North America.
Normal degree days are calculated using a rolling 20-year average of historical heating degree days. 3) OTHER UTILITY OPERATIONS - STEAM - IPL’s Prairie Creek facility provides steam for IPL’s two high-pressure steam customers in Iowa.
Normal degree days are calculated using a rolling 20-year average of historical heating degree days. 3) OTHER UTILITY OPERATIONS - STEAM - IPL’s Prairie Creek facility provided steam for IPL’s two high-pressure steam customers in Iowa. These customers were each under contract through 2025 for taking minimum quantities of annual steam usage, with certain conditions.
IPL is also engaged in the generation and distribution of steam for two customers in Cedar Rapids, Iowa, which are each under contract through 2025 for taking minimum quantities of annual steam usage, with certain conditions, after which IPL expects to exit the steam business. 2) WPL - is a public utility engaged principally in the generation and distribution of electricity and the distribution and transportation of natural gas to retail customers in select markets in Wisconsin.
IPL also sells electricity to wholesale customers in Illinois and Iowa and was engaged in the generation and distribution of steam for two customers in Cedar Rapids, Iowa, which were each under contract through 2025 for taking minimum quantities of annual steam usage, with certain conditions.
Alliant Energy, IPL and WPL are currently unable to predict with certainty the future outcome or impact of these revised standards, including resolution of ongoing litigation.
In June 2025, the EPA proposed to repeal the May 2024 111(b) revised standards and a final rule is expected in the first half of 2026. Alliant Energy, IPL and WPL are currently unable to predict with certainty the future outcome or impact of these revised standards, including resolution of ongoing or potential litigation.
These standards reflect the degree of emission limitation achievable through the application of the BSER. In December 2024, the EPA proposed updates to the NSPS for combustion turbines built, reconstructed, or modified after December 13, 2024, which would establish more stringent emission limits for nitrogen oxides emissions and retain the current sulfur dioxide emission limits.
These standards reflect the degree of emission limitation achievable through the application of the BSER. In January 2026, EPA finalized updates to the NSPS for combustion turbines built, reconstructed, or modified after December 13, 2024. The rule established revised nitrogen oxides emission limits based on the size, capacity factor, efficiency, and fuel type for new, reconstructed or modified combustion turbines.
Employee Engagement - A workplace where everyone feels meaningful connection to work and company goals is crucial for the success and retention of our employees, to attract future talent and to execute our purpose-driven strategy to serve our customers and build stronger communities.
Award recipients have achieved excellent records in high school, are pursuing a higher education, and may enroll in any accredited two- or four-year college, university or vocational-technical school in the U.S. 5 Table of Contents Employee Engagement - A workplace where everyone feels meaningful connection to work and company goals is crucial for the success and retention of our employees, to attract future talent and to execute our purpose-driven strategy to serve our customers and build stronger communities.
Also, IPL is required to defer a portion of its earnings if its annual regulatory return on common equity exceeds certain levels. Refer to “ Rate Matters ” in MDA for discussion of IPL’s retail electric base rate moratorium from October 2025 through September 2029 approved by the IUC in IPL’s most recent retail electric rate review.
Refer to “ Rate Matters ” in MDA for discussion of IPL’s retail electric base rate moratorium from October 2025 through September 2029 approved by the IUC in IPL’s most recent retail electric rate review. Energy Efficiency - In accordance with Iowa law, IPL is required to file an energy efficiency plan (EEP) every five years with the IUC.
IPL and WPL have coal ash ponds at current and former EGU sites, and active and inactive CCR landfills, that are impacted by this rule. Alliant Energy, IPL and WPL continue to evaluate the revised CCR Rule and are unable to predict with certainty the future outcome or impact of these updates, including resolution of ongoing litigation.
Alliant Energy, IPL and WPL continue to evaluate the revised CCR Rule and are unable to predict with certainty the future outcome or impact of these updates, including resolution of ongoing litigation. Manufactured Gas Plant Sites - Refer to Note 1 6 (e) for discussion of IPL’s and WPL’s MGP sites.
In November 2024, the EPA issued an interim final rule to stay the 2023 rule and re-establish the prior emission caps and allowance allocations, including Wisconsin, pending judicial review. WPL currently receives, and expects to receive in the future, enough CSAPR emission allowances to ensure ongoing compliance without the need to purchase additional allowances or materially curtail operations.
CSAPR establishes state-specific annual sulfur dioxide and nitrogen oxides emission caps and ozone season nitrogen oxides emission caps. IPL and WPL currently receive, and expects to receive in the future, enough CSAPR emission allowances to ensure ongoing compliance without the need to purchase additional allowances or materially curtail operations.
Manufactured Gas Plant Sites - Refer to Note 1 6 (e) for discussion of IPL’s and WPL’s MGP sites. Renewable Energy Standards - Iowa and Wisconsin have renewable energy standards, which establish the minimum amount of energy IPL and WPL must supply from renewable resources.
Renewable Energy Standards - Iowa and Wisconsin have renewable energy standards, which establish the minimum amount of energy IPL and WPL must supply from renewable resources. IPL primarily relies upon renewable energy generated from the wind or solar resources it owns and renewable energy acquired under PPAs to meet these requirements.
The final rule does not apply to EGUs that are retired by January 2032. If WPL’s coal-fired Columbia Energy Center is retired by the end of 2029, the final rule would not be applicable; however, if WPL converts Columbia Unit 1 and/or Unit 2 to natural gas, then the final rule would be applicable for the EGUs that are converted.
The final rule does not apply to EGUs that are retired by January 2032. In addition, the final rule does not impact existing natural gas-fired combustion turbines.
These revisions do not currently apply to Iowa; however, Iowa could be included in a future rule. As a result, Alliant Energy and IPL are currently unable to predict with certainty the future outcome or impacts of these matters.
In February 2026, the EPA finalized a rule to rescind its 2009 finding that GHG contributes to climate change, concluding that regulation of GHG falls outside of the scope of the CAA. Alliant Energy, IPL and WPL are currently unable to predict with certainty the future outcome or impact of these matters, including resolution of ongoing or potential litigation.
Annually, Alliant Energy awards up to 25 scholarships to children of its current employees and eligible retirees. Award recipients have achieved excellent records in high school, are pursuing a higher education, and may enroll in any accredited two- or four-year college, university or vocational-technical school in the U.S.
Annually, Alliant Energy awards up to 25 scholarships to children of its current employees and eligible retirees.
Removed
IPL also sells electricity to wholesale customers in Minnesota (IPL’s related wholesale power agreement expires July 2025), Illinois and Iowa.
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Subsequent to December 31, 2025, IPL exited the steam business. 2) WPL - is a public utility engaged principally in the generation and distribution of electricity and the distribution and transportation of natural gas to retail customers in select markets in Wisconsin.
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Short- and long-term incentive plans have a mix of operational and financial metrics that align employees with strategic corporate goals.
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We also provide a personal family advocate to help employees navigate their healthcare needs as well as other resources to help maintain and improve their health.
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Energy Efficiency - In accordance with Iowa law, IPL is required to file an energy efficiency plan (EEP) every five years with the IUC. An EEP provides a utility’s plan and related budget to achieve specified levels of electric and gas energy savings.
Added
Talent Development and Workforce Readiness - We support all employees in their skill development and career growth, offering several training opportunities, development programs and tuition reimbursement, as well as leadership development and succession planning.
Removed
Electric Generating Unit Environmental Controls Projects - At its sole discretion, IPL may submit an updated emissions plan and budget to the IUC setting out a multi-year plan and budget for managing regulated emissions from its coal-fired EGUs in a cost-effective manner.
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IPL and WPL rely primarily on the use of the ITC and ATC transmission systems, respectively. 6 Table of Contents Natural Gas Act - FERC regulates the transportation and sale for resale of natural gas in interstate commerce under the Natural Gas Act.
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IPL must simultaneously submit this plan and budget to the Iowa Department of Natural Resources for a determination of whether the plan and budget meet state environmental requirements for regulated emissions. The reasonable and prudent costs associated with implementing the approved plan are expected to be included in IPL’s future retail electric rates.
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Also, IPL is required to defer a portion of its earnings if its annual regulatory return on common equity exceeds certain levels. IPL would apply excess earnings to the remaining net book value of IPL’s highest earning asset with advance ratemaking principles based on its authorized return on common equity.
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State plans are subject to EPA approval, and must be submitted by May 2026.
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In June 2025, the EPA proposed to repeal CAA Section 111(d) and a final rule is expected in the first half of 2026. The proposed repeal has delayed the submittal of state plans for EPA approval by the May 2026 deadline.
Removed
In addition, the final rule does not impact existing natural gas-fired combustion turbines, including IPL’s Marshalltown Generating Station and Emery Generating Station, and WPL’s Riverside Energy Center and West Riverside Energy Center; however, these EGUs could be subject to future Section 111(d) rules to reduce CO2 emissions from existing combustion turbines.
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The rule maintained the prior sulfur dioxide emission limits. Alliant Energy, IPL and WPL expect to be able to comply with the updated NSPS requirements and will continue to monitor potential litigation.
Removed
CSAPR establishes state-specific annual sulfur dioxide and nitrogen oxides emission caps and ozone season nitrogen oxides emission caps. In 2023, the EPA finalized revisions to the CSAPR state-specific ozone season nitrogen oxides emission caps and utility-specific emission allowances for certain states, including Wisconsin, beginning in 2023; however, these revisions were stayed by the Supreme Court in June 2024.
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In December 2025, EPA finalized an extended timeframe for the new requirements, which must now be implemented no later than December 31, 2034.

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Item 1A. Risk Factors

Risk Factors — what could go wrong, per management

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Biggest changeThe impacts on our operations include: our ability to site and construct new energy facilities, such as renewable energy, energy storage projects, or natural gas-fired electric generating units, and recover associated costs; our ability to decommission generating facilities 16 Table of C o ntents and recover related costs and the remaining carrying value of these facilities and related assets; MISO’s resource adequacy process establishing seasonal capacity planning reserve margin and capacity accreditation requirements, as well as additional changes to capacity accreditation, such as the direct loss of load methodology, impact how and when existing and new generating facilities such as IPL’s and WPL’s additional solar generation are accredited with energy capacity, and may require IPL and WPL to adjust their current resource plans, to add resources to meet the requirements of MISO’s seasonal resource adequacy process, or procure capacity whereby such costs might not be recovered in rates; the impact of the lack of availability of existing and new generating facilities has on our accredited capacity for such facilities pursuant to MISO’s seasonal resource adequacy process; IPL’s ability to achieve certain aggregate summer capacity factors under the consumer protection plan for its up to 400 MW of solar generation projects; the rates paid to transmission operators and how those costs are recovered from customers, including our ability to continue to use a transmission rider in Iowa; our ability to site, construct and recover costs for new natural gas pipelines; our ability to recover costs to upgrade our electric and gas distribution systems; the amount of certain sources of energy we must use, such as renewable sources; our ability to purchase generating facilities and recover the costs associated therewith; our ability to sell utility assets and any conditions placed upon the sale of such assets; our ability to enter into purchased power agreements and recover the costs associated therewith; the allocation of expenditures by transmission companies on transmission network upgrades and our ability to recover costs associated therewith; reliability; safety; the issuance of securities and ability to use other financing arrangements for our renewable energy projects; accounting matters; and transactions between affiliates.
Biggest changeThe impacts on our operations include: our ability to site and construct new energy facilities, such as renewable energy, energy storage projects, or natural gas-fired electric generating units (EGUs), and recover associated costs; our ability to decommission generating facilities and recover related costs and the remaining carrying value of these facilities and related assets; MISO’s resource adequacy process establishing seasonal capacity planning reserve margin and capacity accreditation requirements, as well as additional changes to capacity accreditation, such as the direct loss of load methodology, impact how and when existing and new generating facilities such as IPL’s and WPL’s additional solar generation are accredited with energy capacity, and may require IPL and WPL to adjust their current resource plans, to add resources to meet the requirements of MISO’s seasonal resource adequacy process, or procure capacity whereby such costs might not be recovered in rates; legislation or regulation that imposes mandatory integrated resource planning requirements, or materially changes existing resource planning standards, could delay approvals, require revisions to resource plans, increase compliance costs, and impact our ability to timely meet demand for energy from commercial and industrial customers, including data centers; the impact of the lack of availability of existing and new generating facilities on our accredited capacity for such facilities pursuant to MISO’s seasonal resource adequacy process; IPL’s ability to achieve certain aggregate summer capacity factors under the consumer protection plan for its up to 400 MW of solar generation projects; the rates paid to transmission operators and how those costs are recovered from customers, including our ability to continue to use a transmission rider in Iowa; our ability to site, construct and recover costs for new natural gas pipelines; our ability to recover costs to upgrade our electric and gas distribution systems; the amount of certain sources of energy we must use, such as renewable sources; our ability to purchase generating facilities and recover the costs associated therewith; our ability to sell utility assets and any conditions placed upon the sale of such assets; our ability to enter into purchased power agreements and recover the costs associated therewith; the allocation of expenditures by transmission companies on transmission network upgrades and our ability to recover costs associated therewith; reliability; safety; the issuance of securities and ability to use other financing arrangements for our renewable energy projects; accounting matters; and transactions between affiliates.
If we were unable to obtain enough natural gas or coal for our electric generating units under our existing contracts, or to obtain electricity under existing or future purchased power agreements, we could be required to purchase natural gas or coal at higher prices, need to secure higher cost delivery of natural gas or coal, be forced to curtail the operation of our natural gas-fired or coal-fired generating facilities, be forced to purchase electricity from higher-cost generating resources in the MISO energy market and/or be required to purchase replacement capacity to comply with electric demand planning reserve margins.
If we were unable to obtain enough natural gas or coal for our EGUs under our existing contracts, or to obtain electricity under existing or future purchased power agreements, we could be required to purchase natural gas or coal at higher prices, need to secure higher cost delivery of natural gas or coal, be forced to curtail the operation of our natural gas-fired or coal-fired generating facilities, be forced to purchase electricity from higher-cost generating resources in the MISO energy market and/or be required to purchase replacement capacity to comply with electric demand planning reserve margins.
These risks include: the inability to obtain necessary regulatory approvals and permits in a timely 19 Table of C o ntents manner; adverse interpretation or enforcement of permit conditions; changes in applicable laws or regulations; changes in costs of materials, equipment, commodities, fuel or labor including due to inflation, tariffs or labor issues; delays caused by construction accidents or injuries; shortages in materials, equipment, or qualified labor; changes to the scope or timing of the projects; general contractors, subcontractors, or equipment not performing as required under their contracts; the inability to agree to contract terms or disputes in contract terms; the inability to successfully resolve warranty claims; poor initial cost estimates; work stoppages; adverse weather conditions; government actions; legal action; unforeseen engineering or technology issues; limited access to capital or other financing arrangements; and other adverse economic conditions.
These risks include: the inability to obtain necessary regulatory approvals and permits in a timely manner; adverse interpretation or enforcement of permit conditions; changes in applicable laws or regulations; changes in costs of materials, equipment, commodities, fuel or labor including due to inflation, tariffs or labor issues; delays caused by construction accidents or injuries; shortages in materials, equipment, or qualified labor; changes to the scope or timing of the projects; general contractors, subcontractors, or equipment not performing as required under their contracts; the inability to agree to contract terms or disputes in contract terms; the inability to successfully resolve warranty claims; poor initial cost estimates; work stoppages; adverse weather conditions; government actions; legal action; unforeseen engineering or technology issues; limited access to capital or other financing arrangements; and other adverse economic conditions.
We are dependent on the capital markets and could be negatively impacted by disruptions in the capital markets - Successful implementation of our strategy is dependent upon our ability to access the capital markets. We have forecasted capital expenditures of approximately $11 billion over the next four years.
We are dependent on the capital markets and could be negatively impacted by disruptions in the capital markets - Successful implementation of our strategy is dependent upon our ability to access the capital markets. We have forecasted capital expenditures of approximately $13 billion over the next four years.
Energy demand may decrease due to many things, including economic conditions, proliferation of customer and third party- 18 Table of C o ntents owned generation, technological advances that reduce the costs of renewable energy and energy storage solutions for our customers, government policies, such as the Inflation Reduction Act of 2022, which incentivize customer and third party-owned generation, loss of service territory or franchises, energy efficiency measures, changes in customer usage due to rate design changes, such as time of use rates, technological advances that improve energy efficiency, third-party disrupters, loss of wholesale customers, loss of customers that pursue their own renewable projects to achieve specific sustainability goals, and the adverse impact of tariffs on our customers.
Energy demand may decrease due to many things, including economic conditions, proliferation of customer and third party-owned generation, technological advances that reduce the costs of renewable energy and energy storage solutions for our customers, government policies, such as the Inflation Reduction Act of 2022, which incentivize customer and third party-owned generation, loss of service territory or franchises, energy efficiency measures, changes in customer usage due to rate design changes, such as time of use rates, technological advances that improve energy efficiency, third-party disrupters, loss of wholesale customers, loss of customers that pursue their own renewable projects to achieve specific sustainability goals, and the adverse impact of tariffs on our customers.
The loss of customers, the inability to replace those customers with new customers, and the decrease in demand for energy could negatively impact our financial condition and results of operations. Our utility business is seasonal and may be adversely affected by the impacts of weather - Electric and gas utility businesses are seasonal businesses.
The loss of customers, the inability to replace those customers with new customers, and the decrease in demand for energy could negatively impact our financial condition and results of operations. 19 Table of Contents Our utility business is seasonal and may be adversely affected by the impacts of weather - Electric and gas utility businesses are seasonal businesses.
IPL and WPL may not receive an adequate amount of rate relief to recover all costs and earn their authorized rates of return, rates may be reduced, rate refunds may be required, rate adjustments may not be approved on a timely basis, costs may not be otherwise recovered through rates, earnings above certain thresholds may be required to be refunded, recovery of capital expenditures, including those for electric distribution systems, above certain thresholds may be capped or not be allowed, rates may be temporarily frozen, such as IPL’s current retail electric rate base moratorium through September 2029, laws, rules or settlements may limit the ability to file rate adjustments or the period covered by a rate adjustment, regulatory decisions may limit the ability to defer recovery of and a return on prudently incurred costs in between rate reviews, certain rate base items may not receive a full weighted average cost of capital, and authorized rates of return on capital may be reduced.
IPL and WPL may not receive an adequate amount of rate relief to recover all costs and earn their authorized rates of return, rates may be reduced, rate refunds may be required, rate adjustments may not be approved on a timely basis, costs may not be otherwise recovered through rates, earnings above certain thresholds may be required to be refunded or be used to reduce existing rate base of assets with higher levels of authorized return on equity, recovery of capital expenditures, including those for electric distribution systems, above certain thresholds may be capped or not be allowed, rates may be temporarily frozen, such as IPL’s current retail electric rate base moratorium through September 2029, laws, rules or settlements may limit the ability to file rate adjustments or the period covered by a rate adjustment, regulatory decisions may limit the ability to defer recovery of and a return on prudently incurred costs in between rate reviews, certain rate base items may not receive a full weighted average cost of capital, and authorized rates of return on capital may be reduced.
Natural gas market prices have been volatile in the past and could be volatile in the future due to additional future regulations, increased demand including due to increased liquified natural gas demand from foreign countries, limited global suppliers of natural gas, periods of extremely cold temperatures or disruption in supply caused by major storms or pipeline explosions.
Natural gas market prices have been volatile in the past and could be volatile in the future due to additional future regulations, increased demand including due to new natural gas-fired generating facilities, increased liquified natural gas demand from foreign countries, limited global suppliers of natural gas, periods of extremely cold temperatures or disruption in supply caused by major storms or pipeline explosions.
If we do not receive adequate dividends and distributions from our subsidiaries, then we may not be able to make, or may have to reduce, dividend payments on Alliant Energy common stock. We are subject to risks related to inflation - We have experienced a significant increase in inflation.
If we do not receive adequate dividends and distributions from our subsidiaries, then we may not be able to make, or may have to reduce, dividend payments on Alliant Energy common stock. 22 Table of Contents We are subject to risks related to inflation - We have experienced a significant increase in inflation.
These laws and regulations have imposed, and proposed laws and regulations could impose in the future, additional costs on our utility operations and requirements that impact our ability to continue operating electric generating units. We have incurred, and will continue to incur, capital and other expenditures to comply with these and other environmental laws and regulations.
These laws and regulations have imposed, and proposed laws and regulations could impose in the future, additional costs on our utility operations and requirements that impact our ability to continue operating EGUs. We have incurred, and will continue to incur, capital and other expenditures to comply with these and other environmental laws and regulations.
The pace and feasibility to fully achieve decarbonization is also contingent on the future development and full-scale deployment of emerging energy technologies and supporting infrastructure, as well as electrification of other economic sectors. 17 Table of C o ntents Changing economic conditions and drivers to support significant load growth, including data centers, could influence electric demand.
The pace and feasibility to fully achieve decarbonization is also contingent on the future development and full-scale deployment of emerging energy technologies and supporting infrastructure, as well as electrification of other economic sectors. Changing economic conditions and drivers to support significant load growth, including data centers, could influence electric demand.
This could affect the timing of retirement for our existing coal-fired electric generating units, and our need to add new fossil-fueled generation resources due to growing electric loads.
This could affect the timing of retirement for our existing coal-fired EGUs, and our need to add new fossil-fueled generation resources due to growing electric loads.
If energy storage facilities are not completed in the anticipated timeframe or investment tax credits are not able to be generated or sold due to the repeal or amendment of the Inflation Reduction Act of 2022, we may experience adverse impacts on our financial condition and results of operations.
If energy storage facilities are not completed in the anticipated timeframe or investment tax credits are not able to be generated or sold due to the repeal or amendment of the Inflation Reduction Act of 2022, or new limitations imposed by the OBBB Act, we may experience adverse impacts on our financial condition and results of operations.
Storms and natural disasters may impact our customers and the resulting reduced demand for energy could cause 20 Table of C o ntents lower sales and revenues, which may not be replaced or recovered in rates, or rate recovery may be delayed. Any of these items could adversely impact our financial condition and results of operations.
Storms and natural disasters may impact our customers and the resulting reduced demand for energy could cause lower sales and revenues, which may not be replaced or recovered in rates, or rate recovery may be delayed. Any of these items could adversely impact our financial condition and results of operations.
A high usage customer may decide not to take energy, take less energy than anticipated, or not take service on the anticipated schedule, due to changes in business needs, construction delays, technological advances that improve energy efficiency, or other factors, which may result in lower demand for energy than anticipated.
A large load growth customer may decide not to take energy, take less energy than anticipated, or not take service on the anticipated schedule, due to changes in business needs, construction delays, technological advances that improve energy efficiency, or other factors, which may result in lower demand for energy than anticipated.
Demand for energy from high usage customers may impact our business - The ability to serve significant new commercial or industrial customers on contract rates, including data centers, may require certain regulatory approvals, and the activities and costs related to the construction, acquisition or contracts for additional generation capacity and transmission required to meet the high demands of such customers could be significant.
The ability to serve significant new commercial or industrial customers on contract rates, including data centers, may require certain regulatory approvals, and the activities and costs related to the construction, acquisition or contracts for additional generation capacity and transmission required to meet the high demands of such customers could be significant.
In addition, our tax liability is determined by our taxable income multiplied by the current tax rates in effect. If the federal or state tax rates are increased, or we become subject to a corporate alternative minimum tax, we may experience adverse impacts to our financial condition and results of operations until those rates are reflected in our regulatory filings.
If the federal or state tax rates are increased, state income tax apportionment is increased, or we become subject to a corporate alternative minimum tax, we may experience adverse impacts to our financial condition and results of operations until those rates are reflected in our regulatory filings.
We face risks associated with operating electric and natural gas infrastructure - The operation of electric generation and distribution infrastructure involves many risks, including start-up risks, breakdown or failure of equipment, fires developing from our power lines, transformers, energy storage facilities, or substations, dam failure at one of our hydroelectric facilities, the dependence on a specific fuel source, including the supply and transportation of fuel, the risk of performance below expected or contracted levels of output or efficiency, members of the public or contractors coming into contact with our infrastructure, public and employee safety, operator error, and ruptured oil and chemical tanks.
Inability to recover higher costs, or inability to complete projects in a timely manner, could adversely impact our financial condition and results of operations. 20 Table of Contents We face risks associated with operating electric and natural gas infrastructure - The operation of electric generation and distribution infrastructure involves many risks, including start-up risks, breakdown or failure of equipment, fires developing from our power lines, transformers, energy storage facilities, or substations, dam failure at one of our hydroelectric facilities, the dependence on a specific fuel source, including the supply and transportation of fuel, the risk of performance below expected or contracted levels of output or efficiency, members of the public or contractors coming into contact with our infrastructure, public and employee safety, operator error, and ruptured oil and chemical tanks.
This could have an adverse impact by increasing costs and delaying the construction, maintenance or repair of items that are needed to support normal operations or are necessary to our construction projects to implement our strategy. Inability to recover higher costs, or inability to complete projects in a timely manner, could adversely impact our financial condition and results of operations.
This could have an adverse impact by increasing costs and delaying the construction, maintenance or repair of items that are needed to support normal operations or are necessary to our construction projects to implement our strategy.
Our subsidiaries are separate and distinct legal entities and have no obligation to pay any amounts to Alliant Energy, whether by dividends, distributions, loans or other payments.
The primary sources of funds for Alliant Energy to pay dividends to its shareowners are dividends and distributions from its subsidiaries, primarily its utility subsidiaries. Our subsidiaries are separate and distinct legal entities and have no obligation to pay any amounts to Alliant Energy, whether by dividends, distributions, loans or other payments.
Environmental Protection Agency’s proposed rules to regulate GHG emissions at fossil-fuel fired electric generating units and specific impacts, including state plans to implement the emissions reductions, remains uncertain. There could also be changes by the current or future Presidential or Gubernatorial Administrations.
Environmental Protection Agency’s proposed rules to regulate GHG emissions at fossil-fuel fired EGUs and specific impacts, including state plans to implement the emissions reductions, remains uncertain. There could also be changes by the current or future Presidential or Gubernatorial Administrations. Various legislative and regulatory proposals to address climate change at the national, state and local levels continue to be introduced.
Increases in interest rates will cause the cost of capital to increase and may cause the price of our equity securities to decline. Any disruptions in capital markets could adversely impact our ability to implement our strategy. We rely on our strong credit ratings to access the credit markets.
The inability to access these funds due to federal action or other reasons may increase our costs and interest rates. Increases in interest rates will cause the cost of capital to increase and may cause the price of our equity securities to decline. Any disruptions in capital markets could adversely impact our ability to implement our strategy.
Changes to certain tax elections, tax regulations and future taxable income could negatively impact our financial condition and results of operations - We have significantly reduced our federal and state income tax obligations through tax planning strategies and the utilization of bonus depreciation deductions for certain expenditures for property.
We cannot provide any assurance regarding the potential impacts of climate change or related policies and regulations to reduce GHG emissions on our operations, which could have a material adverse impact on our financial condition and results of operations. 18 Table of Contents Changes to certain tax elections, tax regulations and future taxable income could negatively impact our financial condition and results of operations - We have significantly reduced our federal and state income tax obligations through tax planning strategies and the utilization of bonus depreciation deductions for certain expenditures for property.
Changes to regional and local climate trends such as the frequency, seasonality, and severity of weather conditions could directly and indirectly impact our company. Acute and chronic physical risks could disrupt our operations or affect our property. Furthermore, it could affect the timing of peak demand and overall energy consumption of our customers.
This could result in rapid increased demand for alternative non-fossil fuel energy sources and economy-wide electrification. Changes to regional and local climate trends such as the frequency, seasonality, and severity of weather conditions could directly and indirectly impact our company. Acute and chronic physical risks could disrupt our operations or affect our property.
Our utility business is developing energy storage facilities, which are expected to generate investment tax credits. Investment tax credits are dependent on the tax capitalized costs of the qualifying generating facilities and the applicable tax credit rate.
Investment tax credits are dependent on the tax capitalized costs of the qualifying generating facilities and the applicable tax credit rate.
Provisions of the Wisconsin Utility Holding Company Act may limit our ability to invest in or grow our non-utility activities and may deter potential purchasers who might be willing to pay a premium for our stock.
Changes to these regulations could materially increase our costs or cause us to reconsider our strategy, which could have a material adverse impact on our financial condition and results of operations. 17 Table of Contents Provisions of the Wisconsin Utility Holding Company Act may limit our ability to invest in or grow our non-utility activities and may deter potential purchasers who might be willing to pay a premium for our stock.
IPL and WPL have entered into conditional commitments with the U.S. Department of Energy’s Loan Programs Office for loan guarantees of approximately $3 billion in aggregate and WPL has been selected for additional grants. The inability to access these funds due to federal action or other reasons may increase our costs and interest rates.
IPL and WPL have entered into conditional commitments with the U.S. Department of Energy Office of Energy Dominance Financing, formerly the Loan Programs Office, for loan guarantees of approximately $3 billion in aggregate and WPL has been selected for additional grants.
In addition, the cost of repairing damage to our facilities and infrastructure caused by acts of terrorism, and the loss of revenue if such events prevent us from providing utility service to our customers, could adversely impact our financial condition and results of operations.
In addition, the cost of repairing damage to our facilities and infrastructure caused by acts of terrorism, and the loss of revenue if such events prevent us from providing utility service to our customers, could adversely impact our financial condition and results of operations. 21 Table of Contents We may not be able to fully recover costs related to commodity prices - We have natural gas and coal supply and transportation contracts in place for some of the natural gas and coal we require to generate electricity.
Any work stoppage experienced in connection with negotiations of 21 Table of C o ntents collective bargaining agreements could adversely affect our financial condition and results of operations as well as our ability to implement our strategy.
Any work stoppage experienced in connection with negotiations of collective bargaining agreements could adversely affect our financial condition and results of operations as well as our ability to implement our strategy. We are subject to limitations on our ability to pay dividends - Alliant Energy is a holding company with no significant operations of its own.
The inability or delays in obtaining regulatory approvals or securing additional capacity or transmission, due to supply chain risk, operational risk, or other factors, may impact our ability, or the cost, to provide energy to new customers, the contract rates may not fully recover the costs, the contracts may increase counterparty credit risk, and the costs to provide service may be higher than expected.
The inability or delays in obtaining regulatory approvals with acceptable conditions or providing sufficient generation or securing transmission, due to supply chain risk, operational risk, or other factors, may impact our ability, or the cost, to provide energy to new customers.
We have sold, and continue to plan to sell, a substantial amount of our eligible renewable tax credits.
We have sold, and continue to plan to sell, a substantial amount of our eligible renewable tax credits. However, the One Big Beautiful Bill Act (OBBB Act) includes significant changes to renewable tax credits, including accelerating the termination of production tax credits and investment tax credits.
The contract rates for high usage customers are subject to regulatory approvals and our regulatory authorities may change the rates we can charge and the costs that can be recovered.
The individual customer rates for large load growth customers are subject to regulatory approvals and our regulatory authorities may change the rates we can charge and the costs that can be recovered. As a result, we may experience adverse impacts on our financial condition and results of operations.
Regulation or legislation mandating GHG emissions reductions or other clean energy standards affecting utility companies could materially increase costs, causing some electric generating units to be uneconomical to operate or maintain. We are vulnerable to potential risks associated with the construction of electric generating units that may extend to our supply chain and natural gas operations.
Potential future requirements to reduce GHGs from the energy and manufacturing sectors could affect our operations in various ways. Regulation or legislation mandating GHG emissions reductions or other clean energy standards affecting utility companies could materially increase costs, causing some EGUs to be uneconomical to operate or maintain.
We may not be able to fully recover costs related to commodity prices - We have natural gas and coal supply and transportation contracts in place for some of the natural gas and coal we require to generate electricity. We also have transportation and supply agreements in place to facilitate delivery of natural gas to our customers.
We also have transportation and supply agreements in place to facilitate delivery of natural gas to our customers.
For example, WPL has notified the PSCW that its solar generating facility developments have exceeded the approved costs. We may not be able to meet capacity requirements, including new demand from high usage customers, to comply with electric demand planning reserve margins if a construction project is not completed or is delayed.
We may not be able to meet capacity requirements, including new demand from high usage customers, to comply with electric demand planning reserve margins if a construction project is not completed or is delayed. Inability to recover costs, or inability to complete projects or recover costs in a timely manner, could adversely impact our financial condition and results of operations.
Regulation of oil and gas production could affect our upstream supply of natural gas for electricity generation and to provide directly to our residential and business customers from our local distribution company. This could result in rapid increased demand for alternative non-fossil fuel energy sources and economy-wide electrification.
We are vulnerable to potential risks associated with the construction of EGUs that may extend to our supply chain and natural gas operations. Regulation of oil and gas production could affect our upstream supply of natural gas for electricity generation and to provide directly to our residential and business customers from our local distribution company.
Removed
Our regulators or legislatures could change regulations or laws to permit third parties to provide renewable energy directly to our customers without being treated as a utility, potentially causing a competitive disadvantage for us.
Added
Risks Related to Data Center and Other Large Load Growth Customers Demand from data centers and other large load growth customers may impact our business - Our ability to manage the development and implementation of complex business opportunities related to the growing demand for data centers may be limited by financial, operational, or regulatory factors.
Removed
Changes to these regulations could materially increase our costs or cause us to reconsider our strategy, which could have a material adverse impact on our financial condition and results of operations.
Added
We may enter into agreements requiring significant capital investment in generation and transmission capacity for large load growth customers before realizing any potential returns. We may not be able to affordably and timely construct generation, or cause transmission companies to affordably and timely construct transmission infrastructure to meet potential load growth from any large load growth customer.
Removed
Various legislative and regulatory proposals to address climate change at the national, state and local levels continue to be introduced. Potential future requirements to reduce GHGs from the energy and manufacturing sectors could affect our operations in various ways.
Added
The addition of large load growth customers may increase the concentration of sales, and increase revenue and earnings volatility. We may not be able to adequately protect against the risks inherent in relying on rapid growth within a small number of large customers in a single industry.
Removed
We cannot provide any assurance regarding the potential impacts of climate change or related policies and regulations to reduce GHG emissions on our operations, which could have a material adverse impact on our financial condition and results of operations.
Added
The individual customer rates may not provide sufficient revenues to fully recover the costs, the contracts with large load growth customers may increase counterparty credit risk, and the costs to provide service may be higher than expected. Large load growth customers may not be able to meet obligations in our contracts, including the obligation to pay any termination charges.
Removed
The addition of high usage customers may increase the concentration of sales, and increase revenue and earnings volatility. These factors could negatively impact our financial condition and results of operations.
Added
Additionally, if pipeline expansions needed for new gas‑fired generation are delayed or not approved, we may be unable to meet peak requirements for data center load, increasing market purchases or capacity procurement costs.
Removed
Inability to recover costs, or inability to complete projects or recover costs in a timely manner, could adversely impact our financial condition and results of operations.
Added
Any of these circumstances could adversely affect our business, financial condition, results of operations and growth prospects. 16 Table of Contents Laws, regulations, and opposition to data centers may impact our business - Federal, state or local legislation, rulemaking, or siting standards that specifically restrict or delay the zoning, siting or operation of data centers could reduce or defer expected load growth and impair cost recovery for associated infrastructure.
Removed
We are subject to limitations on our ability to pay dividends - Alliant Energy is a holding company with no significant operations of its own. The primary sources of funds for Alliant Energy to pay dividends to its shareowners are dividends and distributions from its subsidiaries, primarily its utility subsidiaries.
Added
Community opposition to data centers—driven by concerns about land use, water consumption, generation emissions, noise, or traffic—could result in permitting delays, litigation, project cancellations, or additional mitigation costs, reducing expected load growth.
Removed
ITEM 1B. UNRESOLVED STAFF COMMENTS None. 22 Table of C o ntents
Added
Legislative or regulatory changes that enable large load growth customers, including data centers, to own or procure on-site generation or to self-supply through sources behind-the-meter or behind-the-meter arrangements could materially reduce retail sales, shift cost recovery to remaining customers, and impact our ability to earn authorized rates of return.
Added
We may not be able to meet our resource adequacy requirements if GHG regulations require us to shut down fossil fuel generating facilities before we can build new generating facilities to meet growing demand for electricity.
Added
Furthermore, it could affect the timing of peak demand and overall energy consumption of our customers.
Added
These changes may materially limit our ability to sell or transfer renewable tax credits at reasonable terms in future periods.
Added
In addition, our tax liability is determined by our taxable income multiplied by the current tax rates in effect.
Added
The OBBB Act’s early termination of production tax credits for projects beginning construction more than 12 months after enactment may also limit our ability to qualify new facilities for future production tax credits. Our utility business is developing energy storage facilities, which are expected to generate investment tax credits.
Added
The Inflation Reduction Act and related guidance also include limitations on the use of components and/or financing from entities with ties to certain foreign countries.
Added
If our generation or energy storage projects include equipment or subcomponents sourced from entities with ties to certain foreign countries, related production or investment tax credits may be reduced or denied, which could increase customer costs and adversely affect our financial condition.
Added
The OBBB Act further expands limitations on the use of components and/or financing from entities with ties to certain foreign countries, which could reduce or disqualify renewable tax credits for generation and energy storage projects.
Added
We may not realize anticipated or expected growth from large load growth customers, due to many factors, including changes in customers’ goals, changes in environmental policies, improvements in energy efficiency or technology, or competition from other companies.
Added
We may not be able to provide sufficient transmission capacity in a timely manner or transmission providers may be unable to timely provide transmission upgrades to enable connecting new generation to the grid, which could delay expected system load demand from large load growth customers such as data centers, expose us to market purchases and reduce expected revenues.
Added
We rely on our strong credit ratings to access the credit markets.

Item 1C. Cybersecurity

Cybersecurity — threats and controls disclosure

4 edited+2 added−1 removed11 unchanged
Biggest changeHowever, measures that we take to avoid, detect, mitigate or recover from cybersecurity breaches or incidents may be insufficient or become ineffective, and there are no assurances that cybersecurity breaches or incidents will not impact our business operations and strategy, results of operations and financial condition.
Biggest changeHowever, measures that we take to avoid, detect, mitigate or recover from cybersecurity breaches or incidents may be insufficient or become ineffective, and there are no assurances that cybersecurity breaches or incidents will not impact our business operations and strategy, results of operations and financial condition. 23 Table of Contents We maintain a cybersecurity program that includes development and implementation of policies, procedures and tools designed to help ensure availability of critical operations, information technology and telecommunication systems and safeguard sensitive informa tion.
Management, including the CIO, provides reports approximately quarterly to the Board regarding risks, threats, the threat landscape, assessments of and improvements to the cybersecurity program, and internal response preparedness. 23 Table of C o ntents
Management, including the CIO, provides reports approximately quarterly to the Board regarding risks, threats, the threat landscape, assessments of and improvements to the cybersecurity program, and internal response preparedness.
The CIO oversees a team dedicated to the support of cybersecurity tools and the overall cybersecurity program. The CIO reports to the Executive Vice President and CFO.
The CIO oversees a team dedicated to the support of cybersecurity tools and the overall cybersecurity program. The CIO reports to the Executive Vice President and Chief Strategy Officer.
This assessment is conducted by a third party periodically and internally at least annually. We are also required to comply with cybersecurity standards under the North American Electric Reliability Corporation (NERC) Critical Infrastructure Protection and by the Department of Homeland Security Transportation Security Administration.
We are also required to comply with cybersecurity standards under the North American Electric Reliability Corporation (NERC) Critical Infrastructure Protection and by the Department of Homeland Security Transportation Security Administration.
Removed
We maintain a cybersecurity program that includes development and implementation of policies, procedures and tools designed to help ensure availability of critical operations, information technology and telecommunication systems and safeguard sensitive information . The cybersecurity program is assessed against industry standards, including certain Center for Internet Security critical security controls.
Added
The cybersecurity program is assessed against industry standards, including the National Institute of Standards and Technology Cybersecurity Fram ework. This assessment is conducted by a third party periodically and internally at least annually.
Added
The Audit Committee provides oversight of policies on risk assessment, controls, and accounting risk exposure, reviews cybersecurity disclosures in filings with the Securities and Exchange Commission, and reviews internal audit reports related to cybersecurity processes. The Operations Committee provides focused oversight of operational and capital‑related cybersecurity and technology matters. 24 Table of Contents

Item 2. Properties

Properties — owned and leased real estate

8 edited+2 added−1 removed1 unchanged
Biggest changeThe principal properties of those subsidiaries are as follows: IPL and WPL Electric - At December 31, 2024, IPL’s and WPL’s facilities by primary fuel type were as follows: IPL Generating In-service Capacity Name of Facility and Location Dates in MW (a) Marshalltown Generating Station (Units 1-3); Marshalltown, IA 2017 652 Emery Generating Station (Units 1-3); Mason City, IA 2004 531 Marshalltown Combustion Turbines (Units 1-3); Marshalltown, IA 1978 105 Burlington Generating Station (Unit 1); Burlington, IA 1968 131 Prairie Creek Generating Station (Unit 4); Cedar Rapids, IA 1967 126 Burlington Combustion Turbines (Units 1-4); Burlington, IA 1994-1996 37 Total Gas 1,582 Upland Prairie (121 Units); Clay and Dickinson Cos., IA 2019 299 Whispering Willow - North (81 Units); Franklin Co., IA 2020 201 Whispering Willow - East (121 Units); Franklin Co., IA 2009 200 Golden Plains (82 Units); Winnebago and Kossuth Cos., IA 2020 200 English Farms (69 Units); Poweshiek Co., IA 2019 172 Richland (53 Units); Sac Co., IA 2020 131 Franklin County (60 Units); Franklin Co., IA 2012 99 Total Wind 1,302 Pleasant Creek (Units 1-2), Linn Co., IA 2024 200 Wever; Lee Co., IA 2024 150 Creston; Union Co., IA 2024 50 Dubuque; Dubuque, IA 2017 5 Marshalltown; Marshalltown, IA 2020 3 Customer-hosted and Community Solar; various locations in IA 2024 11 Total Solar 419 Ottumwa Generating Station (Unit 1); Ottumwa, IA (b) 1981 339 George Neal Generating Station (Unit 4); Sioux City, IA (c) 1979 167 George Neal Generating Station (Unit 3); Sioux City, IA (d) 1975 140 Prairie Creek Generating Station (Units 1 and 3); Cedar Rapids, IA 1958-1997 30 Louisa Generating Station (Unit 1); Louisa, IA (e) 1983 30 Total Coal 706 Lime Creek Combustion Turbines (Units 1-2); Mason City, IA 1991 70 Total Oil 70 Energy Storage; various locations in IA 2019-2023 9 Total Energy Storage 9 Total capacity 4,088 24 Table of C o ntents WPL Generating In-service Capacity Name of Facility and Location Dates in MW (a) Riverside Energy Center (Units 1-3); Beloit, WI 2004 536 West Riverside Energy Center (Units 1-3); Beloit, WI (f) 2020 387 Neenah Energy Facility (Units 1-2); Neenah, WI 2000 292 South Fond du Lac Combustion Turbines (2 Units); Fond du Lac, WI (g) 1994 163 Total Gas 1,378 Bent Tree (122 Units); Freeborn Co., MN 2010-2011 201 Kossuth (56 Units); Kossuth Co., IA 2020 152 Cedar Ridge (41 Units); Fond du Lac Co., WI 2008 68 Forward Wind Energy Center (37 Units); Dodge and Fond du Lac Cos., WI (h) 2008 59 Total Wind 480 Grant County, Grant Co., WI 2024 200 Wood County, Wood Co., WI 2022 150 Onion River, Sheboygan Co., WI 2023 150 Springfield, Dodge Co., WI 2023 100 Wautoma, Waushara Co., WI 2023 99 Crawfish River, Jefferson Co., WI 2023 75 Paddock, Rock Co., WI 2023 65 Bear Creek, Richland Co., WI 2022 50 North Rock, Rock Co., WI 2022 50 Albany, Green Co., WI 2023 50 Beaver Dam, Dodge Co., WI 2023 50 Cassville, Grant Co., WI 2023 50 West Riverside, Beloit, WI (f) 2021 2 Customer-hosted and Community Solar; various locations in WI 2021-2022 4 Total Solar 1,095 Columbia Energy Center (Units 1-2); Portage, WI (i) 1975-1978 598 Edgewater Generating Station (Unit 5); Sheboygan, WI 1985 406 Total Coal 1,004 Prairie du Sac (8 Units); Prairie du Sac, WI 1914-1940 13 Kilbourn (4 Units); Wisconsin Dells, WI 1926-1939 6 Total Hydro 19 Energy Storage; various locations in WI 2022-2023 9 Total Energy Storage 9 Total capacity 3,985 (a) Based on the summer installed generating capacity included in MISO’s resource adequacy process for the planning period from June 2024 through May 2025, except for wind facilities, solar facilities and energy storage, which are based on nameplate capacity.
Biggest changeThe principal properties of those subsidiaries are as follows: IPL and WPL Electric - At December 31, 2025, IPL’s and WPL’s facilities by primary fuel type were as follows: IPL Generating In-service Capacity Name of Facility and Location Dates in MW (a) Marshalltown Generating Station (Units 1-3); Marshalltown, IA 2017 666 Emery Generating Station (Units 1-3); Mason City, IA 2004 531 Marshalltown Combustion Turbines (Units 1-3); Marshalltown, IA 1978 155 Burlington Generating Station (Unit 1); Burlington, IA 1968 143 Prairie Creek Generating Station (Unit 4); Cedar Rapids, IA 1967 126 Burlington Combustion Turbines (Units 1-4); Burlington, IA 1994-1996 34 Total Gas 1,655 Upland Prairie (121 Units); Clay and Dickinson Cos., IA 2019 299 Whispering Willow - North (81 Units); Franklin Co., IA 2020 201 Whispering Willow - East (121 Units); Franklin Co., IA 2009 200 Golden Plains (82 Units); Winnebago and Kossuth Cos., IA 2020 200 English Farms (69 Units); Poweshiek Co., IA 2019 172 Richland (53 Units); Sac Co., IA 2020 131 Franklin County (60 Units); Franklin Co., IA 2012 99 Total Wind 1,302 Pleasant Creek (Units 1-2), Linn Co., IA 2024 200 Wever; Lee Co., IA 2024 150 Creston; Union Co., IA 2024 50 Dubuque; Dubuque, IA 2017 5 Marshalltown; Marshalltown, IA 2020 3 Customer-hosted and Community Solar; various locations in IA 2024-2025 18 Total Solar 426 Ottumwa Generating Station (Unit 1); Ottumwa, IA (b) 1981 336 George Neal Generating Station (Unit 4); Sioux City, IA (c) 1979 165 George Neal Generating Station (Unit 3); Sioux City, IA (d) 1975 143 Prairie Creek Generating Station (Units 1 and 3); Cedar Rapids, IA (e) 1958-1997 37 Louisa Generating Station (Unit 1); Louisa, IA (f) 1983 30 Total Coal 711 Lime Creek Combustion Turbines (Units 1-2); Mason City, IA 1991 72 Total Oil 72 Wever; Lee Co., IA 2025 99 Energy Storage; various locations in IA 2019-2023 9 Total Energy Storage 108 Total capacity 4,274 25 Table of Contents WPL Generating In-service Capacity Name of Facility and Location Dates in MW (a) Riverside Energy Center (Units 1-3); Beloit, WI 2004 530 West Riverside Energy Center (Units 1-3); Beloit, WI (g) 2020 390 Neenah Energy Facility (Units 1-2); Neenah, WI 2000 296 South Fond du Lac Combustion Turbines (2 Units); Fond du Lac, WI (h) 1994 164 Total Gas 1,380 Bent Tree (122 Units); Freeborn Co., MN 2010-2011 201 Kossuth (56 Units); Kossuth Co., IA 2020 152 Cedar Ridge (41 Units); Fond du Lac Co., WI 2008 68 Forward Wind Energy Center (37 Units); Dodge and Fond du Lac Cos., WI (i) 2008 59 Total Wind 480 Grant County, Grant Co., WI 2024 200 Wood County, Wood Co., WI 2022 150 Onion River, Sheboygan Co., WI 2023 150 Springfield, Dodge Co., WI 2023 100 Wautoma, Waushara Co., WI 2023 99 Crawfish River, Jefferson Co., WI 2023 75 Paddock, Rock Co., WI 2023 65 Bear Creek, Richland Co., WI 2022 50 North Rock, Rock Co., WI 2022 50 Albany, Green Co., WI 2023 50 Beaver Dam, Dodge Co., WI 2023 50 Cassville, Grant Co., WI 2023 50 West Riverside, Beloit, WI (f) 2021 2 Customer-hosted and Community Solar; various locations in WI 2021-2025 11 Total Solar 1,102 Columbia Energy Center (Units 1-2); Portage, WI (j) 1975-1978 596 Edgewater Generating Station (Unit 5); Sheboygan, WI 1985 405 Total Coal 1,001 Prairie du Sac (8 Units); Prairie du Sac, WI 1914-1940 13 Kilbourn (4 Units); Wisconsin Dells, WI 1926-1939 6 Total Hydro 19 Grant County, Grant Co., WI 2025 100 Wood County, Wood Co., WI 2025 75 Energy Storage; various locations in WI 2022-2023 9 Total Energy Storage 184 Total capacity 4,166 (a) Based on the summer installed generating capacity included in MISO’s resource adequacy process for the planning period from June 2025 through May 2026, except for wind facilities, solar facilities and energy storage, which are based on nameplate capacity.
AEF - AEF’s principal properties included in “Property, plant and equipment, net” on Alliant Energy’s balance sheet at December 31, 2024 were as follows: Non-utility Generation - Includes the Sheboygan Falls Energy Facility, a 347 MW, simple-cycle, natural gas-fired facility near Sheboygan Falls, Wisconsin that was placed in service in 2005 and is leased to WPL.
AEF - AEF’s principal properties included in “Property, plant and equipment, net” on Alliant Energy’s balance sheet at December 31, 2025 were as follows: Non-utility Generation - Includes the Sheboygan Falls Energy Facility, a 347 MW, simple-cycle, natural gas-fired facility near Sheboygan Falls, Wisconsin that was placed in service in 2005 and is leased to WPL.
(f) Represents WPL’s 56.6% ownership interest, which is operated by WPL. (g) Represents Units 2 and 3, which WPL owns. WPL also operates, but does not own, South Fond du Lac Combustion Turbines Units 1 and 4. (h) Represents WPL’s 42.64% ownership interest, which is operated by Invenergy Services, LLC.
(f) Represents IPL’s 4% ownership interest, which is operated by MidAmerican Energy Company. (g) Represents WPL’s 56.6% ownership interest, which is operated by WPL. (h) Represents Units 2 and 3, which WPL owns. WPL also operates, but does not own, South Fond du Lac Combustion Turbines Units 1 and 4.
Refer to Note 9 for information regarding WPL’s lease of the Sheboygan Falls Energy Facility from AEF’s Non-utility Generation business. Corporate Services - Corporate Services’ property included in “Property, plant and equipment, net” on Alliant Energy’s balance sheet at December 31, 2024 consisted primarily of computer software, and the corporate headquarters building located in Madison, Wisconsin.
Corporate Services - Corporate Services’ property included in “Property, plant and equipment, net” on Alliant Energy’s balance sheet at December 31, 2025 consisted primarily of computer software, and the corporate headquarters building located in Madison, Wisconsin.
Travero - Includes a short-line rail freight service in Iowa; a Mississippi River barge, rail and truck freight terminal in Illinois; wind turbine blade recycling services; and a rail-served warehouse in Iowa. Development-ready Sites - includes various rail-served and ready-to-build manufacturing and industrial sites throughout Iowa and Wisconsin, with access to various airports, interstate freeways and Alliant Energy’s electric services.
Development-ready Sites - includes various rail-served and ready-to-build manufacturing and industrial sites throughout Iowa and Wisconsin, with access to various airports, interstate freeways and Alliant Energy’s electric services.
The summer installed generating capacity included in MISO’s resource adequacy process for the planning period from June 2024 through May 2025 for the Sheboygan Falls Energy Facility was 298 MW.
The summer installed generating capacity included in MISO’s resource adequacy process for the planning period from June 2025 through May 2026 for the Sheboygan Falls Energy Facility was 298 MW. Travero - Includes a short-line rail freight service in Iowa; a Mississippi River barge, rail and truck freight terminal in Illinois; and a rail-served warehouse in Iowa.
(b) Represents IPL’s 48% ownership interest, which is operated by IPL. (c) Represents IPL’s 25.695% ownership interest, which is operated by MidAmerican Energy Company. (d) Represents IPL’s 28% ownership interest, which is operated by MidAmerican Energy Company. (e) Represents IPL’s 4% ownership interest, which is operated by MidAmerican Energy Company.
(b) Represents IPL’s 48% ownership interest, which is operated by IPL. (c) Represents IPL’s 25.695% ownership interest, which is operated by MidAmerican Energy Company. (d) Represents IPL’s 28% ownership interest, which is operated by MidAmerican Energy Company. (e) Subsequent to December 31, 2025, IPL retired Prairie Creek Unit 1 and fuel switched Prairie Creek Unit 3 to natural gas.
(i) Represents WPL’s 53.5% ownership interest, which is operated by WPL. IPL and WPL own overhead electric distribution line, underground electric distribution cable and substation distribution transformers, substantially all of which are located in Iowa for IPL and Wisconsin for WPL.
IPL and WPL own overhead electric distribution line, underground electric distribution cable and substation distribution transformers, substantially all of which are located in Iowa for IPL and Wisconsin for WPL. 26 Table of Contents Gas - IPL’s and WPL’s gas properties consist primarily of mains and services, meters, regulating and gate stations and other related transmission and distribution equipment.
Removed
Gas - IPL’s and WPL’s gas properties consist primarily of mains and services, meters, regulating and gate stations and other related transmission and distribution equipment. IPL’s and WPL’s gas distribution facilities include gas mains located in Iowa and Wisconsin, respectively. 25 Table of C o ntents Other - IPL’s other property includes steam service assets.
Added
(i) Represents WPL’s 42.64% ownership interest, which is operated by Invenergy Services, LLC. (j) Represents WPL’s 53.5% ownership interest, which is operated by WPL.
Added
IPL’s and WPL’s gas distribution facilities include gas mains located in Iowa and Wisconsin, respectively. Other - Refer to Note 9 for information regarding WPL’s lease of the Sheboygan Falls Energy Facility from AEF’s Non-utility Generation business.

Item 4. Mine Safety Disclosures

Mine Safety Disclosures — required of mining issuers

6 edited+3 added−2 removed2 unchanged
Biggest changeBarton has served as CEO since February 2023, and as a director since January 2024. Robert J. Durian 54 Alliant Energy, IPL and WPL Mr. Durian has served as Executive VP and Chief Financial Officer (CFO) since February 2020. He previously served as Senior VP and CFO since February 2019.
Biggest changeDurian has served as Executive VP and Chief Financial Officer (CFO) since February 2020. He previously served as Senior VP and CFO since February 2019. David A. de Leon 63 Mr. de Leon has served as Senior VP since January 2019. Mayuri N. Farlinger 43 Ms. Farlinger has served as VP since January 2022.
The executive officers of Alliant Energy, IPL and WPL as of the date of this filing are as follows: Name Age as of Filing Date Registrant Positions Lisa M. Barton 59 Alliant Energy Ms. Barton has served as President and Chief Executive Officer (CEO) and as a director since January 2024.
The executive officers of Alliant Energy, IPL and WPL as of the date of this filing are as follows: Name Age as of Filing Date Positions Lisa M. Barton 60 Ms. Barton has served as President and Chief Executive Officer (CEO) and as a director since January 2024.
He has served as Assistant Controller since November 2021, as Manager - Accounting and Reporting from May 2020 to November 2021, and as Manager - Accounting from May 2018 to April 2020. PART II
He previously served as Assistant Controller since November 2021, as Manager - Accounting and Reporting from May 2020 to November 2021, and as Manager - Accounting from May 2018 to April 2020. PART II
She previously served as President and Chief Operating Officer (COO) since February 2023, as Executive Vice President (VP) and COO of American Electric Power Company, Inc. (AEP) from January 2021 to November 2022, and as Executive VP - Utilities of AEP from January 2020 to December 2020. IPL and WPL Ms.
She previously served as President and Chief Operating Officer (COO) since February 2023, as Executive Vice President (VP) and COO of American Electric Power Company, Inc. (AEP) from January 2021 to November 2022, and as Executive VP - Utilities of AEP from January 2020 to December 2020. Robert J. Durian 55 Mr.
He previously served as Executive VP - External Affairs of AEP since July 2022, as Senior VP - Regulatory and Customer Solutions of AEP from July 2021 to July 2022, and as President and COO of AEP Ohio from January 2019 to July 2021. 26 Table of C o ntents Name Age as of Filing Date Registrant Positions Benjamin M.
He previously served as Executive VP - External Affairs of AEP since July 2022, as Senior VP - Regulatory and Customer Solutions of AEP from July 2021 to July 2022, and as President and COO of AEP Ohio from January 2019 to July 2021. 27 Table of Contents Name Age as of Filing Date Positions Antonio P. Smyth 50 Mr.
She previously served as Director of Operations from January 2020 to December 2021. IPL Ms. Farlinger has served as President since May 2024. Raja Sundararajan 49 Alliant Energy, IPL and WPL Mr. Sundararajan has served as Executive VP since June 2023.
She previously served as Director of Operations from January 2020 to December 2021. Raja Sundararajan 50 Mr. Sundararajan has served as Executive VP and Chief Strategy Officer since January 2026. He previously served as Executive VP since June 2023.
Removed
David A. de Leon 62 Alliant Energy and IPL Mr. de Leon has served as Senior VP since January 2019. WPL Mr. de Leon has served as President since January 2019. Mayuri N. Farlinger 42 Alliant Energy and WPL Ms. Farlinger has served as Vice President since January 2022.
Added
Smyth has served as Executive VP of Power Generation and Gas Strategy since April 2025.
Removed
Bilitz 50 Alliant Energy, IPL and WPL Mr. Bilitz has served as Chief Accounting Officer and Controller since December 2016. Dylan M. Syse 39 Alliant Energy, IPL and WPL Mr. Syse was selected to become Chief Accounting Officer and Controller effective March 2, 2025.
Added
He previously served as Executive VP - Grid Solutions of AEP since December 2024, Executive VP - Grid Solutions & Government Affairs of AEP from April 2023 to December 2024, Senior VP - Grid Solutions of AEP from January 2021 to April 2023, and Senior VP - Transmission Ventures, Strategy & Policy of AEP from October 2018 to December 2020.
Added
Rebecca C. Valcq 50 Ms. Valcq has served as VP since January 2026. She previously served as Assistant Vice President since 2024. From 2019 to 2024, she served as Chair of the Public Service Commission of Wisconsin. Dylan M. Syse 40 Mr. Syse has served as Chief Accounting Officer and Controller since March 2025.

Item 5. Market for Registrant's Common Equity

Market for Common Equity — stock, dividends, buybacks

4 edited+0 added−0 removed2 unchanged
Biggest changeCommon Stock Repurchases - A summary of Alliant Energy common stock repurchases for the quarter ended December 31, 2024 was as follows: Total Number Average Price Total Number of Shares Maximum Number (or Approximate of Shares Paid Per Purchased as Part of Dollar Value) of Shares That May Period Purchased (a) Share Publicly Announced Plan Yet Be Purchased Under the Plan (a) October 1 to October 31 6,487 $59.67 — N/A November 1 to November 30 2,933 62.65 — N/A December 1 to December 31 19 59.99 — N/A 9,439 60.60 — (a) All shares were purchased on the open market and held in a rabbi trust under the DCP.
Biggest changeCommon Stock Repurchases - A summary of Alliant Energy common stock repurchases for the quarter ended December 31, 2025 was as follows: Total Number Average Price Total Number of Shares Maximum Number (or Approximate of Shares Paid Per Purchased as Part of Dollar Value) of Shares That May Period Purchased (a) Share Publicly Announced Plan Yet Be Purchased Under the Plan (a) October 1 to October 31 5,449 $67.76 — N/A November 1 to November 30 2,723 68.10 — N/A December 1 to December 31 48 66.30 — N/A 8,220 67.86 — (a) All shares were purchased on the open market and held in a rabbi trust under the DCP.
ITEM 5. MARKET FOR REGISTRANTS’ COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES Common Stock Data - Alliant Energy’s common stock trades on the Nasdaq Global Select Market under the symbol “LNT,” and the closing sales price at December 31, 2024 was $59.14.
ITEM 5. MARKET FOR REGISTRANTS’ COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES Common Stock Data - Alliant Energy’s common stock trades on the Nasdaq Global Select Market under the symbol “LNT,” and the closing sales price at December 31, 2025 was $65.01.
Shareowners - At December 31, 2024, there were 19,293 holders of record of Alliant Energy’s common stock, including holders through Alliant Energy’s Shareowner Direct Plan. Alliant Energy is the sole common shareowner of all 13,370,788 and 13,236,601 shares of IPL and WPL common stock, respectively, currently outstanding.
Shareowners - At December 31, 2025, there were 18,130 holders of record of Alliant Energy’s common stock, including holders through Alliant Energy’s Shareowner Direct Plan. Alliant Energy is the sole common shareowner of all 13,370,788 and 13,236,601 shares of IPL and WPL common stock, respectively, currently outstanding.
As a result, there is no established public trading market for the common stock of either IPL or WPL. Dividends - In October 2024, Alliant Energy announced an increase in its targeted 2025 annual common stock dividend to $2.03 per share, which is equivalent to a quarterly rate of $0.5075 per share, beginning with the February 2025 dividend payment.
As a result, there is no established public trading market for the common stock of either IPL or WPL. Dividends - In November 2025, Alliant Energy announced an increase in its targeted 2026 annual common stock dividend to $2.14 per share, which is equivalent to a quarterly rate of $0.535 per share, beginning with the February 2026 dividend payment.

Item 6. [Reserved]

Selected Financial Data — reserved (removed by SEC in 2021)

3 edited+1 added−1 removed0 unchanged
Biggest changeFinancial Statements and Supplementary Data 46 Alliant Energy Corporation 47 Interstate Power and Light Company 53 Wisconsin Power and Light Company 59 Combined Notes to Consolidated Financial Statements 65 1. Summary of Significant Accounting Policies 65 2. Regulatory Matters 71 3. Property, Plant and Equipment 74 4. Jointly-owned Electric Utility Plant 75 5. Receivables 76 6. Investments 77 7.
Biggest changeFinancial Statements and Supplementary Data 48 Alliant Energy Corporation 49 Interstate Power and Light Company 55 Wisconsin Power and Light Company 61 Combined Notes to Consolidated Financial Statements 67 1. Summary of Significant Accounting Policies 67 2. Regulatory Matters 73 3. Property, Plant and Equipment 76 4. Jointly-owned Electric Utility Plant 77 5. Receivables 77 6. Investments 78 7.
Item 6. [Reserv ed ] 27 Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations 27 Item 7A. Quantitative and Qualitative Disclosures About Market Risk 46 Item 8.
Item 6. [Reserv ed ] 28 Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations 28 Item 7A. Quantitative and Qualitative Disclosures About Market Risk 48 Item 8.
Common Equity 77 8 . Debt 78 9 . Leases 81 1 0 . Revenues 82 1 1 . Income Taxes 83 1 2 . Benefit Plans 85 1 3 . Asset Retirement Obligations 94 1 4 . Derivative Instruments 94 1 5 . Fair Value Measurements 95 1 6 . Commitments and Contingencies 97 1 7 .
Common Equity 79 8 . Debt 80 9 . Leases 84 1 0 . Revenues 85 1 1 . Income Taxes 86 1 2 . Benefit Plans 89 1 3 . Asset Retirement Obligations 97 1 4 . Derivative Instruments 97 1 5 . Fair Value Measurements 99 1 6 . Commitments and Contingencies 101 1 7 .
Removed
Segments of Business 100 1 8 . Related Parties 101
Added
Segments of Business 103 1 8 . Related Parties 106 Item 9. Changes in and Disagreements With Accountants on Accounting and Financial Disclosure 106 Item 9A. Controls and Procedures 106 Item 9B. Other Information 109

Item 7. Management's Discussion & Analysis

Management's Discussion & Analysis (MD&A) — revenue / margin commentary

134 edited+52 added−43 removed63 unchanged
Biggest changeAlliant Energy’s Non-utility and Parent net income decreased by $16 million in 2024 compared to 2023, primarily due to higher financing expense. 29 Table of C o ntents Net Income Variances - The following items contributed to increased (decreased) net income for 2024 compared to 2023 (in millions): Alliant Energy IPL WPL Revenues: Changes in electric utility (Refer to details below ) $27 ($14) $41 Changes in gas utility (Refer to details below ) (75) (50) (25) Changes in other utility 2 — 2 Changes in total revenues (46) (64) 18 Operating expenses: Changes in electric production fuel and purchased power (Refer to details below ) 108 13 96 Changes in electric transmission service (Refer to details below ) (30) 3 (33) Changes in cost of gas sold (Refer to details below ) 75 43 33 Asset valuation charge for IPL’s Lansing Generating Station in 2024 (Refer to Note 2 for details) (60) (60) — Changes in other operation and maintenance (Refer to details below ) (1) (5) (8) Changes in depreciation and amortization (Higher primarily due to solar generation placed in service in 2024 and 2023, as well as WPL’s amortization of liquidated damages related to West Riverside procurement contracts, which resulted in reductions to depreciation and amortization expenses in 2023, and updated electric depreciation rates for IPL effective October 1, 2024) (96) (16) (77) Changes in taxes other than income taxes (7) (3) (4) Changes in total operating expenses (11) (25) 7 Changes in operating income (57) (89) 25 Other income and deductions: Changes in interest expense (Higher primarily due to financings completed in 2024 and 2023) (55) (22) (16) Changes in AFUDC (Primarily due to changes in levels of CWIP balances related to solar generation and energy storage, and IPL’s refurbishment of the existing Franklin County wind farm) (25) 22 (47) Changes in Other 6 14 (11) Changes in total other income and deductions (74) 14 (74) Changes in income before income taxes (131) (75) (49) Changes in income taxes (Refer to Note 1 1 for details) 118 71 49 Changes in net income ($13) ($4) $— 30 Table of C o ntents Electric and Gas Revenues and Sales Summary - Electric and gas revenues (in millions), and MWh and Dth sales (in thousands), were as follows: Electric Gas Revenues MWhs Sold Revenues Dths Sold 2024 2023 2024 2023 2024 2023 2024 2023 Alliant Energy Retail $3,009 $3,008 24,569 24,940 $419 $495 43,489 46,405 Sales for resale: Wholesale 200 213 2,783 2,859 N/A N/A N/A N/A Bulk power and other 86 71 5,620 4,730 N/A N/A N/A N/A Transportation/Other 77 53 57 58 46 45 123,386 115,177 $3,372 $3,345 33,029 32,587 $465 $540 166,875 161,582 IPL Retail $1,662 $1,661 13,620 13,909 $223 $273 21,640 23,128 Sales for resale: Wholesale 61 62 750 766 N/A N/A N/A N/A Bulk power and other (6) 11 1,138 1,465 N/A N/A N/A N/A Transportation/Other 30 27 32 32 27 27 43,075 43,232 $1,747 $1,761 15,540 16,172 $250 $300 64,715 66,360 WPL Retail $1,347 $1,347 10,949 11,031 $196 $222 21,849 23,277 Sales for resale: Wholesale 139 151 2,033 2,093 N/A N/A N/A N/A Bulk power and other 92 60 4,482 3,265 N/A N/A N/A N/A Transportation/Other 47 26 25 26 19 18 80,311 71,945 $1,625 $1,584 17,489 16,415 $215 $240 102,160 95,222 Sales Trends and Temperatures - Alliant Energy’s retail electric sales volumes decreased 1% in 2024 compared to 2023, primarily due to changes in sales volumes at IPL’s industrial customers due to standby service customers that can use other generation, and changes in temperatures.
Biggest changeNet Income Variances - The following items contributed to increased (decreased) net income for 2025 compared to 2024 (in millions): Alliant Energy IPL WPL Revenues: Changes in electric utility (Refer to details below ) $325 $149 $176 Changes in gas utility (Refer to details below ) 60 15 45 Changes in other utility (3) (2) (1) Changes in non-utility (1) — — Changes in total revenues 381 162 220 Operating expenses: Changes in electric production fuel and purchased power (Refer to details below ) (114) (14) (100) Changes in electric transmission service (Refer to details below ) (12) (5) (7) Changes in cost of gas sold (Refer to details below ) (39) (7) (32) Asset valuation charge for IPL’s Lansing Generating Station in 2024 (Refer to Note 2 for details) 60 60 — Changes in other operation and maintenance (Refer to details below ) (64) (15) (27) Changes in depreciation and amortization (Higher primarily due to solar generation placed in service in 2024 and updated electric depreciation rates for IPL effective October 1, 2024) (74) (59) (13) Changes in taxes other than income taxes 1 1 1 Changes in total operating expenses (242) (39) (178) Changes in operating income 139 123 42 Other income and deductions: Changes in interest expense (Higher primarily due to financings completed in 2024 and 2025) (63) (34) (8) Changes in equity income from unconsolidated investments, net (Refer to Note 6 for details) (1) — — Changes in AFUDC 14 13 1 Changes in Other (4) (5) (4) Changes in total other income and deductions (54) (26) (11) Changes in income before income taxes 85 97 31 Changes in income taxes (Refer to Note 1 1 for details) 35 (2) 25 Changes in net income $120 $95 $56 31 Table of Contents Electric and Gas Revenues and Sales Summary - Electric and gas revenues (in millions), and MWh and Dth sales (in thousands), were as follows: Electric Gas Revenues MWhs Sold Revenues Dths Sold 2025 2024 2025 2024 2025 2024 2025 2024 Alliant Energy Retail $3,305 $3,009 25,122 24,569 $472 $419 49,363 43,489 Sales for resale: Wholesale 184 200 2,565 2,783 N/A N/A N/A N/A Bulk power and other 164 86 5,386 5,620 N/A N/A N/A N/A Transportation/Other 44 77 56 57 53 46 123,141 123,386 $3,697 $3,372 33,129 33,029 $525 $465 172,504 166,875 IPL Retail $1,801 $1,662 13,882 13,620 $234 $223 23,710 21,640 Sales for resale: Wholesale 39 61 481 750 N/A N/A N/A N/A Bulk power and other 28 (6) 1,777 1,138 N/A N/A N/A N/A Transportation/Other 28 30 31 32 31 27 44,489 43,075 $1,896 $1,747 16,171 15,540 $265 $250 68,199 64,715 WPL Retail $1,504 $1,347 11,240 10,949 $238 $196 25,653 21,849 Sales for resale: Wholesale 145 139 2,084 2,033 N/A N/A N/A N/A Bulk power and other 136 92 3,609 4,482 N/A N/A N/A N/A Transportation/Other 16 47 25 25 22 19 78,652 80,311 $1,801 $1,625 16,958 17,489 $260 $215 104,305 102,160 Sales Trends and Temperatures - Alliant Energy’s retail electric sales volumes increased 2% in 2025 compared to 2024, primarily due to changes in temperatures and higher sales to commercial and industrial customers.
In May 2024, legislation was enacted in Iowa related to the advance rate-making principles for certain generation and energy storage investments located in Iowa.
Advance Rate-making Principles In May 2024, legislation was enacted in Iowa related to the advance rate-making principles for certain generation and energy storage investments located in Iowa.
Alliant Energy, IPL, and WPL also continue to evaluate the impact of these final rules and resulting remediation plans on their financial condition and results of operations. Technology - Alliant Energy, IPL and WPL currently plan to make investments in technology to enhance productivity and efficiency through automation, customer self-service and telework.
Alliant Energy, IPL, and WPL also continue to evaluate the impact of these final rules and resulting remediation plans on their financial condition and results of operations. Technology - Alliant Energy, IPL and WPL currently plan to make investments in technology to enhance productivity and efficiency through automation and customer self-service.
Upon exercise of such options and the resulting sales, WPL received proceeds from the sales in 2023 and 2024. Refer to “ Customer Investments ” for additional information.
Upon exercise of such options and the resulting sales, WPL received proceeds from the sales in 2024. Refer to “ Customer Investments ” for additional information.
Refer to Note 1(c) for discussion of $216 million and $98 million of proceeds from renewable tax credits transferred to other corporate taxpayers in 2024 and 2023, respectively. • Reductions in Iowa corporate income tax rates resulting from tax reform enacted in 2022 are expected to provide cost benefits to IPL’s electric and gas customers in the future.
Refer to Note 1(c) for discussion of $285 million, $216 million and $98 million of proceeds from renewable tax credits transferred to other corporate taxpayers in 2025, 2024 and 2023, respectively. • Reductions in Iowa corporate income tax rates resulting from tax reform enacted in 2022 are expected to provide cost benefits to IPL’s electric and gas customers in the future.
In addition, at December 31, 2024, there were various other liabilities included on the balance sheets that, due to the nature of the liabilities, the timing of payments cannot be estimated. OTHER MATTERS Market Risk Sensitive Instruments and Positions - Primary market risk exposures are associated with commodity prices, counterparty credit risk, investment prices and interest rates.
In addition, at December 31, 2025, there were various other liabilities included on the balance sheets that, due to the nature of the liabilities, the timing of payments cannot be estimated. OTHER MATTERS Market Risk Sensitive Instruments and Positions - Primary market risk exposures are associated with commodity prices, counterparty credit risk, investment prices and interest rates.
The IUC’s order included the following provisions: • Annual retail electric base rate increase of $185 million, with customers receiving partially offsetting credits for the first 12 months through a tax benefit rider, and a subsequent retail electric base rate moratorium through September 2029; • During the moratorium, IPL may request updated rates if its actual return on common equity is 100 or more basis points below the authorized return on common equity for a single calendar year or 50 or more basis points below the authorized return on common equity for two consecutive years, and/or if a material change in laws or regulations causes the moratorium to become unsustainable; • Annual retail gas base rate increase of $10 million; 36 Table of C o ntents • Electric earnings sharing mechanism beginning in calendar year 2025, where IPL would apply excess earnings to the remaining net book value of IPL’s highest earning asset with advance ratemaking principles (currently the Emery Generation Station) based on its authorized return on common equity as follows; Threshold Above Authorized Return on Common Equity Sharing First 50 basis points 75% customers, 25% IPL >50 to 100 basis points 50% customers, 50% IPL >100 to 150 basis points 25% customers, 75% IPL >150 basis points 100% customers • Investment tax credits resulting from renewable generation and energy storage projects may be utilized to offset any revenue deficiency on an annual basis up to IPL’s return on common equity threshold; any remaining investment tax credits, net of the cost of transferability, that are not used to offset any revenue deficiency, will be deferred by IPL and carried forward to offset any revenue deficiency in future years; • Creation of an individual customer rate tariff, which would allow IPL to attract new load growth to its service territory; • Electric distribution system investment cap not to exceed $900 million in aggregate or $325 million in any given year from 2026 through 2029, with certain exceptions; • IPL to retain renewable production tax credits from new generation resources not included in base rates and the repowering of existing wind farms, including the Franklin County wind farm refurbishment, as well as retain energy margins for new generation resources and energy storage; • Discontinuation of the renewable energy rider; and • A return of the remaining net book value of the Lansing Generating Station; however, the IUC’s order does not include a return on the remaining net book value of Lansing, resulting in Alliant Energy and IPL recording a pre-tax non-cash charge of $60 million to “Asset valuation charge for IPL’s Lansing Generating Station” in their income statements in 2024.
The IUC’s order included the following provisions: • Annual retail electric base rate increase of $185 million, with customers receiving partially offsetting credits for the first 12 months through a tax benefit rider totaling $52 million and $16 million in 2025 and 2024, respectively, and a subsequent retail electric base rate moratorium through September 2029; • During the moratorium, IPL may request updated rates if its actual return on common equity is 100 or more basis points below the authorized return on common equity for a single calendar year or 50 or more basis points below the authorized return on common equity for two consecutive years, and/or if a material change in laws or regulations causes the moratorium to become unsustainable; • Annual retail gas base rate increase of $10 million; • Electric earnings sharing mechanism beginning in calendar year 2025, where IPL would apply excess earnings to the remaining net book value of IPL’s highest earning asset with advance ratemaking principles (currently the Emery Generation Station) based on its authorized return on common equity as follows; Threshold Above Authorized Return on Common Equity Sharing First 50 basis points 75% customers, 25% IPL >50 to 100 basis points 50% customers, 50% IPL >100 to 150 basis points 25% customers, 75% IPL >150 basis points 100% customers • Investment tax credits resulting from renewable generation and energy storage projects may be utilized to offset any revenue deficiency on an annual basis up to IPL’s return on common equity threshold; any remaining investment tax credits, net of the cost of transferability, that are not used to offset any revenue deficiency, will be deferred by IPL and carried forward to offset any revenue deficiency in future years; • Creation of an individual customer rate tariff, which would allow IPL to attract new load growth to its service territory; • Electric distribution system investment cap not to exceed $900 million in aggregate or $325 million in any given year from 2026 through 2029, with certain exceptions; • IPL to retain renewable production tax credits from new generation resources not included in base rates and the repowering of existing wind farms, including the Franklin County wind farm refurbishment, as well as retain energy margins for new generation resources and energy storage; • Discontinuation of the renewable energy rider; and • A return of the remaining net book value of the Lansing Generating Station; however, the IUC’s order does not include a return on the remaining net book value of Lansing, resulting in Alliant Energy and IPL recording a pre-tax non-cash charge of $60 million to “Asset valuation charge for IPL’s Lansing Generating Station” in their income statements in 2024.
Changes may result from a number of reasons, including changes in expected load growth, regulatory requirements, changing legislation, not obtaining favorable and acceptable regulatory approval on certain projects, changing costs of projects due to market conditions, improvements in technology, and improvements to ensure resiliency and reliability of the electric and gas distribution systems.
Changes may result from a number of reasons, including changes in expected load growth, regulatory requirements, changing legislation, not obtaining favorable and acceptable regulatory approval on certain projects, changing costs of projects due to market conditions and the impact of tariffs, improvements in technology, and improvements to ensure resiliency and reliability of the electric and gas distribution systems.
The following discussion and analysis should be read in conjunction with the Financial Statements and Notes included in this report. Unless otherwise noted, all “per share” references in MDA refer to earnings per diluted share. In addition, this MDA includes certain financial information for 2024 compared to 2023.
The following discussion and analysis should be read in conjunction with the Financial Statements and Notes included in this report. Unless otherwise noted, all “per share” references in MDA refer to earnings per diluted share. In addition, this MDA includes certain financial information for 2025 compared to 2024.
Alliant Energy, IPL and WPL maintain credit policies intended to minimize overall credit risk and actively monitor these policies to reflect changes and scope of operations. Alliant Energy, IPL, and WPL conduct credit reviews for certain counterparties, and employ credit risk controls such as letters of credit, parental guarantees, master netting agreements and termination provisions.
Alliant Energy, IPL and WPL maintain credit policies intended to minimize overall credit risk and actively monitor these policies to reflect changes and scope of operations. Alliant Energy, IPL, and WPL conduct credit reviews for certain counterparties, and employ credit risk controls such as letters of credit, surety bonds, parental guarantees, master netting agreements and termination provisions.
Alliant Energy’s and IPL’s critical assumptions and judgments for 2024 included estimates of qualifying deductions for repairs expenditures, allocation of mixed service costs and state depreciation, and costs related to retirement or removal of depreciable property due to the impact of Iowa rate-making principles on such property-related differences.
Alliant Energy’s and IPL’s critical assumptions and judgments for 2025 included estimates of qualifying deductions for repairs expenditures, allocation of mixed service costs and state depreciation, and costs related to retirement or removal of depreciable property due to the impact of Iowa rate-making principles on such property-related differences.
The purchase commitment from the third party to which IPL sells its receivables expires in March 2026. In 2024 and 2023, IPL evaluated the third party that purchases IPL’s receivable assets under the Receivables Agreement and believes that the third party is a VIE; however, IPL concluded consolidation of the third party was not required.
The purchase commitment from the third party to which IPL sells its receivables expires in March 2026. In 2025 and 2024, IPL evaluated the third party that purchases IPL’s receivable assets under the Receivables Agreement and believes that the third party is a VIE; however, IPL concluded consolidation of the third party was not required.
At December 31, 2024, Alliant Energy, IPL and WPL had no uncertain tax positions recorded as liabilities. Refer to Note 1 2 (a) for anticipated pension and OPEB funding amounts. Refer to “ Construction and Acquisition Expenditures ” above for additional information on construction and acquisition programs.
At December 31, 2025, Alliant Energy, IPL and WPL had no uncertain tax positions recorded as liabilities. Refer to Note 1 2 (a) for anticipated pension and OPEB funding amounts. Refer to “ Construction and Acquisition Expenditures ” above for additional information on construction and acquisition programs.
Certain Financial Commitments - Contractual Obligations - Alliant Energy, IPL and WPL have various long-term contractual obligations as of December 31, 2024, which include long-term debt maturities in Note 8 (b) , operating and finance leases in Note 9 , capital purchase obligations in Note 1 6 (a) , and other purchase obligations in Note 1 6 (b) .
Certain Financial Commitments - Contractual Obligations - Alliant Energy, IPL and WPL have various long-term contractual obligations as of December 31, 2025, which include long-term debt maturities in Note 8 (b) , operating and finance leases in Note 9 , capital purchase obligations in Note 1 6 (a) , and other purchase obligations in Note 1 6 (b) .
Regulatory assets and regulatory liabilities are recognized in accordance with the rulings of applicable federal and state regulators, and future regulatory rulings may impact the carrying value and accounting treatment of regulatory assets and regulatory liabilities. Note 2 provides details of the nature and amounts of regulatory assets and regulatory liabilities assessed at December 31, 2024.
Regulatory assets and regulatory liabilities are recognized in accordance with the rulings of applicable federal and state regulators, and future regulatory rulings may impact the carrying value and accounting treatment of regulatory assets and regulatory liabilities. Note 2 provides details of the nature and amounts of regulatory assets and regulatory liabilities assessed at December 31, 2025.
Alliant Energy is currently evaluating the impact of potential additional large load growth customers and MISO’s seasonal resource adequacy requirements on its resource plans and will update these generation investment plans as needed in the future.
Alliant Energy is currently evaluating the impact of potential additional demand from large load growth customers and MISO’s seasonal resource adequacy requirements on its resource plans and will update these generation investment plans as needed in the future.
Alliant Energy, IPL and WPL are working with MISO, state regulatory commissions and other regulatory agencies, as required, to determine the timing of these actions, which are subject to change depending on operational, regulatory, market and other factors. Refer to Note 3 for additional details on Columbia Units 1 and 2, and Edgewater Unit 5.
Alliant Energy, IPL and WPL are working with MISO, state regulatory commissions and other regulatory agencies, as required, to determine the timing of these actions, which are subject to change depending on operational, regulatory, market and other factors. Refer to Note 3 for additional details on Columbia Units 1 and 2.
The most significant provisions of the legislation for Alliant Energy, IPL and WPL relate to a 10-year extension of tax credits for clean energy projects, a new production tax credit for eligible solar projects, a new stand-alone investment tax credit for energy storage projects and the right to transfer renewable tax credits generated after 2022 to other corporate taxpayers.
The most significant provisions of the legislation for Alliant Energy, IPL and WPL relate to a 10-year extension of tax credits for clean energy projects, a new production tax credit for eligible solar projects, a standalone investment tax credit for energy storage projects, and the right to transfer renewable tax credits generated after 2022 to other corporate taxpayers.
Refer to N ote 1 4 for additional information on ratings triggers for commodity contracts accounted for as derivatives. Off-Balance Sheet Arrangements - Special Purpose Entities - IPL maintains a Receivables Agreement whereby it may sell its customer accounts receivables, unbilled revenues and certain other accounts receivables to a third party through wholly-owned and consolidated special purpose entities.
Refer to N ote 1 4 for additional information on ratings triggers for commodity contracts accounted for as derivatives. 44 Table of Contents Off-Balance Sheet Arrangements - Special Purpose Entities - IPL maintains a Receivables Agreement whereby it may sell its customer accounts receivables, unbilled revenues and certain other accounts receivables to a third party through wholly-owned and consolidated special purpose entities.
Short-term Debt - In December 2024, Alliant Energy, IPL and WPL amended and extended their single revolving credit facility agreement, which expires in December 2029 and is discussed in Note 8 (a) . There are currently 14 lenders that participate in the credit facility, with respective commitments ranging from $25 million to $130 million.
Short-term Debt - In December 2025, Alliant Energy, IPL and WPL amended and extended their single revolving credit facility agreement, which expires in December 2030 and is discussed in Note 8 (a) . There are currently 14 lenders that participate in the credit facility, with respective commitments ranging from $25 million to $130 million.
The following table shows the impacts of changing certain key actuarial assumptions discussed above (in millions): Defined Benefit Pension Plans OPEB Plans Change in Actuarial Assumption Impact on Projected Benefit Obligation at December 31, 2024 Impact on 2025 Net Periodic Benefit Costs Impact on Accumulated Benefit Obligation at December 31, 2024 Impact on 2025 Net Periodic Benefit Costs Alliant Energy 1% change in discount rate $85 $7 $10 $— 1% change in expected rate of return N/A 7 N/A 1 IPL 1% change in discount rate 39 3 4 — 1% change in expected rate of return N/A 3 N/A 1 WPL 1% change in discount rate 38 3 4 — 1% change in expected rate of return N/A 3 N/A — Contingencies - Assumptions and judgments are made each reporting period regarding the future outcome of contingent events.
The following table shows the impacts of changing certain key actuarial assumptions discussed above (in millions): Defined Benefit Pension Plans OPEB Plans Change in Actuarial Assumption Impact on Projected Benefit Obligation at December 31, 2025 Impact on 2026 Net Periodic Benefit Costs Impact on Accumulated Benefit Obligation at December 31, 2025 Impact on 2026 Net Periodic Benefit Costs Alliant Energy 1% change in discount rate $83 $7 $10 $— 1% change in expected rate of return N/A 7 N/A 1 IPL 1% change in discount rate 39 3 4 — 1% change in expected rate of return N/A 3 N/A 1 WPL 1% change in discount rate 37 3 4 — 1% change in expected rate of return N/A 3 N/A — Contingencies - Assumptions and judgments are made each reporting period regarding the future outcome of contingent events.
The most significant provisions of this legislation for Alliant Energy would allow IPL to include energy storage and nuclear-fired generation projects in the advance rate-making principles request process prior to making these investments in Iowa, and require IPL to obtain a certificate of public convenience, use and necessity (GCU Certificate) from the IUC in order to construct energy storage projects.
The most significant provisions of this legislation for Alliant Energy would allow IPL to include energy storage and nuclear-fired generation projects in the advance rate-making principles request process prior to making these investments in Iowa, and require IPL to obtain a GCU Certificate from the IUC in order to construct energy storage projects.
Long-term Debt - Refer to Note 8 (b) for discussion of issuances and retirements of long-term debt in 2024, and “ Results of Operations ” for discussion of expected issuances and retirements of long-term debt in 2025.
Long-term Debt - Refer to Note 8 (b) for discussion of issuances and retirements of long-term debt in 2025, and “ Results of Operations ” for discussion of expected issuances and retirements of long-term debt in 2026.
Refer to Note 1 1 for discussion of the carryforward positions. As discussed in “ Legislative Matters ,” the Inflation Reduction Act of 2022 provides the right to transfer renewable tax credits to other corporate taxpayers.
Refer to Note 1 1 for discussion of the carryforward positions. 41 Table of Contents As discussed in “ Legislative Matters ,” the Inflation Reduction Act of 2022 provides the right to transfer renewable tax credits to other corporate taxpayers.
Refer to Note 1 2 (a) for discussion of pension plan contributions in 2024 and the current funded levels of pension plans.
Refer to Note 1 2 (a) for discussion of pension plan contributions in 2025 and the current funded levels of pension plans.
Refer to Note 5(b) for additional information regarding IPL’s sales of accounts receivable program. Guarantees and Indemnifications - At December 31, 2024, various guarantees and indemnifications are outstanding related to Alliant Energy’s cash equity ownership interest in a non-utility wind farm, prior divestiture activities and transfers of renewable tax credits to other corporate taxpayers.
Refer to Note 5(b) for additional information regarding IPL’s sales of accounts receivable program. Guarantees and Indemnifications - At December 31, 2025, various guarantees and indemnifications are outstanding related to Alliant Energy’s cash equity ownership interest in a non-utility wind farm, prior divestiture activities, transfers of renewable tax credits to other corporate taxpayers and electric transmission infrastructure.
Assuming the impact of a hypothetical 100 basis point increase in interest rates on variable-rate borrowings and cash amounts outstanding under IPL’s sales of accounts receivable program at December 31, 2024, Alliant Energy’s, IPL’s and WPL’s annual pre-tax expense would increase by approximately $6 million, $1 million and $2 million, respectively.
Assuming the impact of a hypothetical 100 basis point increase in interest rates on variable-rate borrowings and cash amounts outstanding under IPL’s sales of accounts receivable program at December 31, 2025, Alliant Energy’s, IPL’s and WPL’s annual pre-tax expense would increase by approximately $2 million, $2 million and $0 million, respectively.
WPL’s retail electric service is exposed to the impact of changes in commodity prices due largely to the current retail recovery mechanism in place in Wisconsin for fuel-related costs. 43 Table of C o ntents Counterparty Credit Risk - Alliant Energy, IPL, and WPL are exposed to credit risk related to losses resulting from counterparties’ nonperformance of their contractual obligations.
WPL’s retail electric service is exposed to the impact of changes in commodity prices due largely to the current retail recovery mechanism in place in Wisconsin for fuel-related costs. Counterparty Credit Risk - Alliant Energy, IPL, and WPL are exposed to credit risk related to losses resulting from counterparties’ nonperformance of their contractual obligations.
The new legislation also includes a requirement for corporations with income over $1 billion to pay a 15% minimum tax; however, Alliant Energy is currently below this income level.
The legislation also established a requirement for corporations with income over $1 billion to pay a 15% minimum tax; however, Alliant Energy is currently below this income level.
In addition, Alliant Energy, IPL and WPL currently expect a decrease in the effective income tax rate in 2025 compared to 2024 due to additional tax credits from renewable generation and energy storage projects placed in service in 2024 and/or expected to be placed in service in 2025.
Furthermore, Alliant Energy, IPL and WPL currently expect a decrease in the effective income tax rate in 2026 compared to 2025 due to additional renewable tax credits from renewable generation and energy storage projects placed in service in 2025 and/or expected to be placed in service in 2026.
Credit ratings and outlooks as of the date of this report are as follows: 42 Table of C o ntents Standard & Poor’s Ratings Services Moody’s Investors Service Alliant Energy: Corporate/issuer A- Baa2 Commercial paper A-2 P-2 Senior unsecured long-term debt BBB+ N/A Outlook Negative Stable IPL: Corporate/issuer A- Baa1 Commercial paper A-2 P-2 Senior unsecured long-term debt A- Baa1 Outlook Negative Stable WPL: Corporate/issuer A Baa1 Commercial paper A-1 P-2 Senior unsecured long-term debt A Baa1 Outlook Negative Stable Standard & Poor’s Ratings Services and Moody’s Investors Service issued credit ratings of BBB+ and Baa2, respectively, for the senior notes issued by AEF in 2018, 2020, 2022, 2023 and 2024 (with Alliant Energy as guarantor).
Credit ratings and outlooks as of the date of this report are as follows: Standard & Poor’s Ratings Services Moody’s Investors Service Alliant Energy: Corporate/issuer BBB+ Baa2 Commercial paper A-2 P-2 Senior unsecured long-term debt BBB N/A Outlook Stable Stable IPL: Corporate/issuer BBB+ Baa1 Commercial paper A-2 P-2 Senior unsecured long-term debt BBB+ Baa1 Outlook Stable Stable WPL: Corporate/issuer A- Baa1 Commercial paper A-2 P-2 Senior unsecured long-term debt A- Baa1 Outlook Stable Stable Standard & Poor’s Ratings Services and Moody’s Investors Service issued credit ratings of BBB+ and Baa2, respectively, for the senior notes issued by AEF in 2018, 2020, 2022, 2023 and 2024 (with Alliant Energy as guarantor).
WPL estimates the increase (decrease) to electric utility revenues from amounts within the fuel monitoring range were approximately ($4) million and $6 million in 2024 and 2023, respectively.
WPL estimates the increase (decrease) to electric utility revenues from amounts within the fuel monitoring range were approximately $4 million and $(4) million in 2025 and 2024, respectively.
ITEM 7. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS This MDA includes information relating to Alliant Energy, IPL and WPL, as well as AEF and Corporate Services. Where appropriate, information relating to a specific entity has been segregated and labeled as such.
ITEM 7. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS This MDA includes information relating to Alliant Energy, IPL and WPL (collectively, the Utilities), as well as ATC Holdings, AEF and Corporate Services. Where appropriate, information relating to a specific entity has been segregated and labeled as such.
In July 2023, legislation was enacted in Wisconsin, which creates a sales and use tax exemption for the sale of certain property for qualified data centers. The most significant provision of this legislation for Alliant Energy encourages economic development in WPL’s service territory. In August 2022, the Inflation Reduction Act of 2022 was enacted.
In July 2023, legislation was enacted in Wisconsin, which creates a sales and use tax exemption for the sale of certain property for qualified data centers. The most significant provision of this legislation for Alliant Energy encourages economic development in WPL’s service territory.
Carryforward Utilization - Significant federal tax credit carryforwards exist for Alliant Energy, IPL and WPL as of December 31, 2024. Based on projections of current and future taxable income, Alliant Energy, IPL and WPL plan to utilize all of these carryforwards approximately five years before expiration.
Carryforward Utilization - Significant federal tax credit carryforwards exist for Alliant Energy, IPL and WPL as of December 31, 2025. Based on projections of current and future taxable income, Alliant Energy, IPL and WPL plan to utilize all of these carryforwards more than five years before expiration.
This strategy includes the following key elements: 27 Table of C o ntents Providing affordable energy solutions for customers - Alliant Energy’s strategy focuses on affordable energy solutions that support retention and growth of its existing customers and attract new customers to its service territories.
This strategy includes the following key elements: Providing affordable energy solutions for customers - Alliant Energy’s strategy focuses on affordable energy solutions that support retention and growth of existing customers and attract new customers to its service territories.
The order extends, with certain modifications, an earnings sharing mechanism through 2025. Under the earnings sharing mechanism, WPL will defer a portion of its earnings if its annual regulatory return on common equity exceeds 9.95% during the 2024/2025 Test Period. WPL must defer 50% of its excess earnings between 9.95% and 10.55%, and 100% of any excess earnings above 10.55%.
The order extends, with certain modifications, an earnings sharing mechanism through 2027. Under the earnings sharing mechanism, WPL will defer a portion of its earnings if its annual regulatory return on common equity exceeds 10.05% during the 2026/2027 Test Period. WPL must defer 50% of its excess earnings between 10.05% and 10.55%, and 100% of any excess earnings above 10.55%.
The long-lived assets assessed for impairment generally include certain assets within regulated operations that may not be fully recovered from IPL’s and WPL’s customers as a result of regulatory decisions in the future, and assets within non-utility operations that are proposed to be sold or are currently generating operating losses.
These assessments require significant assumptions and judgments by management. The long-lived assets assessed for impairment generally include certain assets within regulated operations that may not be fully recovered from IPL’s and WPL’s customers as a result of regulatory decisions in the future, and assets within non-utility operations that are proposed to be sold or are currently generating operating losses.
Estimated capital expenditures for these planned projects for 2025 through 2028 are included in the “Generation” section in the construction and acquisition table in “ Liquidity and Capital Resources .” Information on IPL’s and WPL’s regulatory filings and/or approvals for future generation and energy storage projects, as well as recently completed projects, are as follows: WPL’s Generation and Energy Storage Projects - Solar - In 2022 through 2024, WPL completed 1,089 MW of new solar generation projects in Wisconsin, including the Grant County facility (200 MW) in 2024.
Estimated capital expenditures for these planned projects for 2026 through 2029 are included in the “Generation” section in the construction and acquisition table in “ Liquidity and Capital Resources .” Information on IPL’s and WPL’s regulatory filings and/or approvals for future generation and energy storage projects, as well as recently completed projects, are as follows: WPL’s Generation and Energy Storage Projects - New Solar - In 2022 through 2024, WPL completed 1,089 MW of new solar generation projects in Wisconsin.
Subject to certain conditions, Alliant Energy, IPL and WPL may exercise two extension options, which would each extend the maturity date by one year.
Subject to certain conditions, Alliant Energy, IPL and WPL may exercise one extension option, which would extend the maturity date by one year.
Alliant Energy, IPL and WPL are utilizing various provisions of the new legislation to enhance the tax benefits expected from their current and planned renewable generation and energy storage projects, including transferring tax credits from such projects to other corporate taxpayers.
Alliant Energy, IPL and WPL are utilizing various provisions of the Inflation Reduction Act of 2022 to enhance the tax benefits expected from their current and planned renewable generation and energy storage projects, including transferring tax credits from such projects to other corporate taxpayers.
The required debt-to-capital ratios compared to the actual debt-to-capital ratios at December 31, 2024 were as follows: Alliant Energy IPL WPL Requirement, not to exceed 65% 65% 65% Actual 60% 48% 48% The debt component of the capital ratios includes, when applicable, long- and short-term debt (excluding non-recourse debt and hybrid securities to the extent the total carrying value of such hybrid securities does not exceed 15% of consolidated capital of the applicable borrower), finance lease obligations, certain letters of credit, guarantees of the foregoing and new synthetic leases.
The required debt-to-capital ratios compared to the actual debt-to-capital ratios at December 31, 2025 were as follows: Alliant Energy IPL WPL Requirement, not to exceed 65% 65% 65% Actual 59% 50% 47% The debt component of the capital ratios includes, when applicable, long- and short-term debt (excluding non-recourse debt and hybrid securities (e.g., junior subordinated notes) to the extent the total carrying value of such hybrid securities does not exceed 15% of consolidated capital of the applicable borrower), finance lease obligations, certain letters of credit, guarantees of the foregoing and new synthetic leases.
Refer to Note 1 3 for further discussion of AROs. Pensions and Other Postretirement Benefits - Alliant Energy, IPL and WPL sponsor various defined benefit pension and OPEB plans that provide benefits to a significant portion of their employees and retirees. Assumptions and judgments are made periodically to estimate the obligations and costs related to their retirement plans.
Pensions and Other Postretirement Benefits - Alliant Energy, IPL and WPL sponsor various defined benefit pension and OPEB plans that provide benefits to a significant portion of their employees and retirees. Assumptions and judgments are made periodically to estimate the obligations and costs related to their retirement plans.
Interest Rate - Alliant Energy, IPL and WPL are exposed to risk resulting from changes in interest rates associated with variable-rate borrowings. In addition, Alliant Energy and IPL are exposed to risk resulting from changes in interest rates on cash amounts outstanding under IPL’s sales of accounts receivable program.
In addition, Alliant Energy and IPL are exposed to risk resulting from changes in interest rates on cash amounts outstanding under IPL’s sales of accounts receivable program.
Estimated decreases to operating income from the impacts of temperatures were as follows (in millions): Electric Gas 2024 2023 Change 2024 2023 Change IPL ($14) ($1) ($13) ($12) ($8) ($4) WPL (15) (5) (10) (10) (6) (4) Total Alliant Energy ($29) ($6) ($23) ($22) ($14) ($8) Electric Sales for Resale - Bulk Power and Other - Bulk power and other volume changes were due to changes in sales in the wholesale energy markets operated by MISO.
Estimated increases (decreases) to operating income from the impacts of temperatures were as follows (in millions): Electric Gas 2025 2024 Change 2025 2024 Change IPL $13 ($14) $27 ($4) ($12) $8 WPL 3 (15) 18 (1) (10) 9 Total Alliant Energy $16 ($29) $45 ($5) ($22) $17 Electric Sales for Resale - Bulk Power and Other - Bulk power and other volume changes were due to changes in sales in the wholesale energy markets operated by MISO.
Key Highlights (refer to “ Customer Investments ” for details) - • Over the next five years, Alliant Energy currently plans to develop and/or acquire new generation investments to add flexibility with evolving load growth, including approximately 1,200 MW of new wind and solar generation in aggregate, approximately 1,000 MW of energy storage, approximately 750 MW of new natural gas resources, refurbishments at approximately 600 MW of existing wind farms, and improvements at approximately 650 MW of existing natural gas-fired EGUs and the conversion of existing coal-fired EGUs to natural gas.
Key Highlights (refer to “ Customer Investments ” for details) - • Over the next five years, Alliant Energy currently plans to develop and/or acquire new generation investments to add flexibility with evolving load growth, including approximately 1,600 MW of new natural gas resources, approximately 1,000 MW of new energy storage, approximately 1,300 MW of new renewable generation, improvements of approximately 410 MW at existing natural gas-fired EGUs, and refurbishments at approximately 450 MW of existing wind farms.
The most significant provision of this program for Alliant Energy encourages economic development in IPL’s service territory. Alliant Energy has various development-ready sites throughout Iowa, including the Big Cedar Industrial Center Mega-site in Cedar Rapids, Iowa, and the Prairie View Industrial Center Super Park in Ames, Iowa.
The most significant provision of this program for Alliant Energy encourages economic development in IPL’s service territory. Alliant Energy has various development-ready sites throughout Iowa, including the Prairie View Industrial Center Super Park in Ames, Iowa and the River City Industrial Center in Mason City, Iowa.
Pension Plan Contributions - Alliant Energy, IPL and WPL currently expect to make $20 million, $1 million and $14 million of pension plan contributions in 2025, respectively, based on the funded status and assumed return on assets for each plan as of the December 31, 2024 measurement date.
Pension Plan Contributions - Alliant Energy, IPL and WPL currently expect to make $23 million, $3 million and $13 million of pension plan contributions in 2026, respectively, based on the funded status and assumed return on assets for each plan as of the December 31, 2025 measurement date.
The single credit facility agreement contains a financial covenant, which requires Alliant Energy, IPL and WPL to maintain certain debt-to-capital ratios in order to borrow under the credit facility. AEF’s term loan credit agreement contains a financial covenant, which requires Alliant Energy to maintain a certain debt-to-capital ratio in order to borrow under the term loan credit agreement.
AEF’s term loan credit agreement contains a financial covenant, which requires Alliant Energy to maintain a certain debt-to-capital ratio in order to borrow under the term loan credit agreement.
In 2023, IPL received authorization from FERC to issue securities in 2024 and 2025 as follows (in millions): Initial Authorization Remaining Capacity as of December 31, 2024 Long-term debt securities issuances in aggregate $1,700 $1,050 Short-term debt securities outstanding at any time (including borrowings from its parent) 400 350 Preferred stock issuances in aggregate 300 300 State Regulatory Financing Authorizations - In March 2023, WPL received authorization from the PSCW to have up to $500 million of short-term borrowings and/or letters of credit outstanding at any time through the expiration date of WPL’s credit facility agreement.
In January 2026, IPL received authorization from FERC to issue securities in 2026 and 2027 as follows (in millions): Initial Authorization Long-term debt securities issuances in aggregate $2,500 Short-term debt securities outstanding at any time (including borrowings from its parent) 400 Preferred stock issuances in aggregate 300 State Regulatory Financing Authorizations - In March 2023, WPL received authorization from the PSCW to have up to $500 million of short-term borrowings and/or letters of credit outstanding at any time through the expiration date of WPL’s credit facility agreement.
WPL’s Retail Electric and Gas Rate Reviews (2024/2025 Forward-looking Test Period) - In December 2023, the PSCW issued an order authorizing annual base rate increases of $49 million and $13 million for WPL’s retail electric and gas customers, respectively, effective January 1, 2024, for the 2024 forward-looking Test Period.
WPL’s Retail Electric and Gas Rate Reviews (2026/2027 Forward-looking Test Period) - In December 2025, the PSCW issued an order authorizing annual base rate increases of $69 million and $7 million for WPL’s retail electric and gas customers, respectively, effective January 1, 2026, for the 2026 forward-looking Test Period.
Department of Energy Office of Clean Energy Demonstrations awarded WPL’s Columbia Energy Storage Project, an approximately 20 MW compressed CO2-based long-duration energy storage system at the Columbia Energy Center site, up to approximately $30 million in grant funding during construction of the project. In addition, in October 2024, the U.S.
Department of Energy Office of Electricity - formerly administered by the Office of Clean Energy Demonstrations - awarded WPL’s Columbia Energy Storage Project, an approximately 20 MW compressed CO2-based long-duration energy storage system at the Columbia Energy Center site, up to approximately $30 million in grant funding during construction of the project.
Existing Natural Gas-Fired Electric Generating Unit Improvements - In April 2024, the PSCW issued orders authorizing WPL to construct improvements at the existing natural gas-fired Neenah Energy Facility and Sheboygan Falls Energy Facility, which would increase the capacity and efficiency of the EGUs.
Existing Natural Gas-Fired Electric Generating Unit Improvements - In April 2024, the PSCW issued orders authorizing WPL to construct improvements at the existing natural gas-fired Neenah Energy Facility and Sheboygan Falls Energy Facility.
Gas Pipeline Expansion - IPL and WPL currently expect to make investments to extend various gas distribution systems to provide natural gas to unserved or underserved areas in their service territories.
Gas Pipeline Expansion - IPL and WPL currently expect to make investments to extend various gas distribution systems to provide natural gas to unserved or underserved areas in their service territories. Additionally, IPL expects to make investments in gas pipelines to serve new natural gas generating facilities.
Gas Pipeline Safety - The Pipeline and Hazardous Materials Safety Administration published various final rules from 2019 through 2024 that updated safety requirements for gas transmission pipelines, and updated procedures were implemented to address these rules. Plans to address certain requirements for specific pipelines were developed and implemented, with identified remediation efforts to be completed by July 2035.
Gas Pipeline Safety - The Pipeline and Hazardous Materials Safety Administration published various final rules from 2019 through 2024 that updated safety requirements for gas transmission pipelines, and updated procedures were implemented to address these rules. Plans to address certain requirements for specific pipelines were developed and implemented.
Gas Utility Revenue Variances - The following items contributed to increased (decreased) gas utility revenues for 2024 compared to 2023 (in millions): Alliant Energy IPL WPL Lower revenues due to changes in gas costs (Refer to Cost of Gas Sold Expense Variances below) ($75) ($42) ($33) Estimated changes in sales volumes caused by temperatures (8) (4) (4) Lower revenues at IPL related to changes in recovery amounts for energy efficiency costs through the energy efficiency rider (mostly offset by changes in energy efficiency expense) (Refer to Note 1(g) ) (6) (6) — Higher revenue requirements (a) (b) 14 2 12 ($75) ($50) ($25) 32 Table of C o ntents (a) In September 2024, the IUC issued an order authorizing an annual base rate increase of $10 million for IPL’s retail gas customers, for the October 2024 through September 2025 forward-looking Test Period.
Gas Utility Revenue Variances - The following items contributed to increased (decreased) gas utility revenues for 2025 compared to 2024 (in millions): Alliant Energy IPL WPL Higher revenues due to changes in gas costs (Refer to Cost of Gas Sold Expense Variances below) $40 $8 $32 Estimated changes in sales volumes caused by temperatures 17 8 9 Higher revenue requirements (a) 6 6 — Lower revenues at IPL related to changes in recovery amounts for energy efficiency costs through the energy efficiency rider (mostly offset by changes in energy efficiency expense) (Refer to Note 1(g) ) (8) (8) — Other 5 1 4 $60 $15 $45 (a) In September 2024, the IUC issued an order authorizing an annual base rate increase of $10 million for IPL’s retail gas customers, for the October 2024 through September 2025 forward-looking Test Period.
Over the next five years, Alliant Energy currently plans to develop and/or acquire new generation investments to add flexibility with evolving load growth, including approximately 1,200 MW of new wind and solar generation in aggregate, approximately 1,000 MW of energy storage, approximately 750 MW of new natural gas resources, refurbishments at approximately 600 MW of existing wind farms, and improvements at approximately 650 MW of existing natural gas-fired EGUs and the conversion of existing coal-fired EGUs to natural gas.
Over the next five years, Alliant Energy currently plans to develop and/or acquire new generation investments to add flexibility with evolving load growth, including approximately 1,600 MW of new natural gas resources, approximately 1,000 MW of new energy storage, approximately 1,300 MW of new renewable generation, improvements of approximately 410 MW at existing natural gas-fired EGUs, and refurbishments at approximately 450 MW of existing wind farms.
In 2023, WPL issued $300 million of 4.95% green bond debentures due 2033, and an amount equal to or in excess of the net proceeds was disbursed for the development and acquisition of its solar EGUs.
In 2024, WPL issued $300 million of 5.375% green bond debentures due 2034, and an amount equal to or in excess of the net proceeds was disbursed for the development and acquisition of its solar EGUs.
Refer to MDA in the combined 2023 Form 10-K for details on certain financial information for 2023 compared to 2022. OVERVIEW Mission, Purpose and Strategy Alliant Energy’s mission is to deliver affordable energy solutions and exceptional service that its customers and the communities it serves count on - affordably, safely, reliably, and sustainably.
Refer to MDA in the combined 2024 Form 10-K for details on certain financial information for 2024 compared to 2023. 28 Table of Contents OVERVIEW Mission, Purpose and Strategy Alliant Energy’s mission is to deliver the energy solutions and exceptional service that its customers and communities count on - affordably, safely, reliably and responsibly.
LEGISLATIVE MATTERS In May 2024, the Major Economic Growth Attraction program was enacted in Iowa, which offers various tax incentives for up to two qualified businesses for certain large-scale projects with capital investments greater than $1 billion constructed on certified sites greater than 250 acres in Iowa.
Refer to Note 1 1 for discussion of Iowa tax reform enacted in 2022. 39 Table of Contents Economic Development In May 2024, the Major Economic Growth Attraction program was enacted in Iowa, which offers various tax incentives for up to two qualified businesses for certain large-scale projects with capital investments greater than $1 billion constructed on certified sites greater than 250 acres in Iowa.
Plant Retirements and Fuel Switching - The current strategy includes the retirement, or fuel switch from coal to natural gas, of various EGUs in the next several years. IPL currently expects to retire Prairie Creek Unit 1 and fuel switch Prairie Creek Unit 3 (65 MW in aggregate) by December 31, 2025.
Plant Retirements and Fuel Switching - The current strategy includes the retirement, or fuel switch from coal to natural gas, of various EGUs. Subsequent to December 31, 2025, IPL retired Prairie Creek Unit 1 and fuel switched Prairie Creek Unit 3 (65 MW in aggregate) to natural gas.
The decrease was primarily due to an asset valuation charge for IPL’s Lansing Generating Station as a result of the IUC order for IPL’s retail electric rate review, estimated temperature impacts on retail electric and gas sales, restructuring and voluntary separation charges, an ARO charge allocated to the steam business at IPL due to the revised CCR Rule, higher depreciation and financing expenses, and lower AFUDC.
The increase was primarily due to higher revenue requirements from capital investments, estimated temperature impacts on retail electric and gas sales, an asset valuation charge for IPL’s Lansing Generating Station as a result of the IUC order for IPL’s retail electric rate review in 2024, restructuring and voluntary separation charges in 2024, and an ARO charge allocated to the steam business at IPL due to the revised CCR Rule in 2024.
Energy Storage - In 2023, the PSCW issued orders authorizing WPL to construct, own and operate energy storage at the Grant County (100 MW) and Wood County (75 MW) solar projects in Wisconsin, which is currently expected to be placed in service in the second half of 2025, and at the Edgewater Generation Station in Wisconsin (approximately 99 MW), which is currently expected to be placed in service in 2026.
New Energy Storage - In 2023, the PSCW issued orders authorizing WPL to construct, own and operate energy storage at the Grant County (100 MW) and Wood County (75 MW) solar projects in Wisconsin, which were placed in service in July and October 2025, respectively, and at the Edgewater Generation Station in Wisconsin (approximately 99 MW), which is currently expected to be placed in service in 2026. 35 Table of Contents In July 2024, the U.S.
Making customer-focused investments - Alliant Energy’s strategic priorities include making significant customer-focused investments toward more reliable, resilient, and sustainable customer energy solutions.
Making customer-focused investments - Alliant Energy’s strategic priorities include making customer-focused investments to provide reliable, resilient, and sustainable energy solutions.
(b) Purchased power expense increased primarily due to higher prices for electricity purchased by IPL and WPL, and higher volumes of electricity purchased at IPL due to lower dispatch of IPL’s EGUs in 2024, partially offset by lower volumes of electricity purchased at WPL due to higher dispatch of WPL’s EGUs in 2024.
(b) Purchased power expense increased primarily due to higher prices for electricity purchased by WPL, partially offset by lower volumes of electricity purchased at IPL.
Refer to the cash flows statements and Note 1 (c) for details of renewable tax credits transferred to other corporate taxpayers in 2023 and 2024. Alliant Energy, IPL and WPL currently intend to transfer all eligible renewable tax credits in the future, and as a result, expect an increase in future cash flows from operating activities.
Refer to the cash flows statements and Note 1 (c) for details of renewable tax credits transferred to other corporate taxpayers. Alliant Energy, IPL and WPL currently intend to transfer all eligible renewable tax credits in the future.
Gas Transportation/Other - Gas transportation/other sales volume changes were largely due to changes in the gas volumes supplied to Alliant Energy’s natural gas-fired EGUs caused by the availability and dispatch of such EGUs. 31 Table of C o ntents Electric Utility Revenue Variances - The following items contributed to increased (decreased) electric utility revenues for 2024 compared to 2023 (in millions): Alliant Energy IPL WPL Higher revenue requirements (a)(b) $240 $85 $155 Higher (lower) sales for resale bulk power and other revenues (c) 15 (17) 32 Deferral of incremental solar generation construction costs at WPL in 2024 (Refer to Note 3 ) 12 — 12 Lower revenues primarily due to changes in retail electric fuel-related costs at WPL, and credits on IPL’s customers’ bills related to production tax credits through its fuel-related cost recovery mechanism (Refer to Electric Production Fuel and Purchased Power Expenses Variances below) (a)(b) (142) (42) (100) Changes in WPL refunds/collections of previous over-/under-collection of retail electric fuel-related costs (offset in electric production fuel and purchased power expenses) (Refer to Note 2 ) (33) — (33) Estimated changes in sales volumes caused by temperatures (23) (13) (10) Lower revenues at IPL due to credits on customers’ bills through the tax benefit rider in 2024 (partially offset by changes in income taxes) (a) (16) (16) — Lower wholesale revenues at WPL primarily due to lower fuel-related costs and lower sales (13) (1) (12) Lower revenues at IPL related to changes in recovery amounts for energy efficiency costs through the energy efficiency rider (mostly offset by changes in energy efficiency expense) (Refer to Note 1(g) ) (13) (13) — Changes in WPL electric fuel-related costs, net of recoveries (d) (10) — (10) Other 10 3 7 $27 ($14) $41 (a) In September 2024, the IUC issued an order authorizing an annual base rate increase of $185 million for IPL’s retail electric customers, with customers receiving partially offsetting credits for the first 12 months through a tax benefit rider, for the October 2024 through September 2025 forward-looking Test Period.
Gas Transportation/Other - Gas transportation/other sales volume changes were largely due to changes in the gas volumes supplied to Alliant Energy’s natural gas-fired EGUs caused by the availability and dispatch of such EGUs. 32 Table of Contents Electric Utility Revenue Variances - The following items contributed to increased (decreased) electric utility revenues for 2025 compared to 2024 (in millions): Alliant Energy IPL WPL Higher revenue requirements (a)(b) $333 $271 $62 Higher sales for resale bulk power and other revenues (c) 78 34 44 Estimated changes in sales volumes caused by temperatures 45 27 18 Changes in WPL refunds/collections of previous over-/under-collection of retail electric fuel-related costs (offset in electric production fuel and purchased power expenses) (Refer to Note 1(g) ) 43 — 43 Higher revenues at IPL related to changes in recovery amounts for energy efficiency costs through the energy efficiency rider (mostly offset by changes in energy efficiency expense) (Refer to Note 1(g) ) 18 18 — Changes in WPL electric fuel-related costs, net of recoveries (d) 8 — 8 Higher (lower) revenues primarily due to changes in retail electric fuel-related costs (Refer to Electric Production Fuel and Purchased Power Expenses Variances below) 5 (10) 15 Lower revenues at IPL due to credits on customers’ bills related to production tax credits through its fuel-related cost recovery mechanism (offset by changes in income taxes) (a) (122) (122) — Lower revenues at IPL due to credits on customers’ bills through the tax benefit rider (partially offset by changes in income taxes) (a) (36) (36) — Lower revenues at IPL from discontinuation of renewable energy rider in 2024 (a) (24) (24) — Lower wholesale revenues at IPL primarily due to lower sales from the expiration of IPL’s wholesale power agreement with Southern Minnesota Energy Cooperative in 2025 (22) (22) — Other (1) 13 (14) $325 $149 $176 (a) In September 2024, the IUC issued an order authorizing an annual base rate increase of $185 million for IPL’s retail electric customers, with customers receiving partially offsetting credits for the first 12 months through a tax benefit rider, for the October 2024 through September 2025 forward-looking Test Period.
Judgments and assumptions are supported by historical data and reasonable projections. Significant changes in these judgments and assumptions could have a material impact on financial condition and results of operations.
Significant changes in these judgments and assumptions could have a material impact on financial condition and results of operations.
Alliant Energy’s net income and EPS attributable to Alliant Energy common shareowners were as follows (dollars in millions, except per share amounts): 2024 2023 Income (Loss) EPS Income (Loss) EPS Utilities and Corporate Services $722 $2.81 $724 $2.86 ATC Holdings 40 0.16 35 0.14 Non-utility and Parent (72) (0.28) (56) (0.22) Alliant Energy Consolidated $690 $2.69 $703 $2.78 Alliant Energy’s Utilities and Corporate Services net income decreased by $2 million in 2024 compared to 2023.
Alliant Energy’s net income and EPS attributable to Alliant Energy common shareowners were as follows (dollars in millions, except per share amounts): 2025 2024 Income (Loss) EPS Income (Loss) EPS Utilities and Corporate Services $875 $3.39 $722 $2.81 ATC Holdings 41 0.16 40 0.16 Non-utility and Parent (106) (0.41) (72) (0.28) Alliant Energy Consolidated $810 $3.14 $690 $2.69 Alliant Energy’s Utilities and Corporate Services net income increased by $153 million in 2025 compared to 2024.
In 2025, IPL currently expects to issue up to $600 million of long-term debt, and AEF and/or Alliant Energy at the parent company level expect to issue up to $600 million of long-term debt in aggregate.
In 2026, IPL and WPL currently expect to issue up to $500 million and $300 million, respectively, of long-term debt, and AEF and/or Alliant Energy at the parent company level expect to issue up to $400 million of long-term debt in aggregate.
Electric Transmission Service Expense Variances - The following items contributed to (increased) decreased electric transmission service expense for 2024 compared to 2023 (in millions): Alliant Energy IPL WPL Changes in regulatory recovery for the difference between actual electric transmission service costs and those costs used to determine rates (Refer to Note 1(g) ) ($28) ($7) ($21) Other (primarily due to changes in transmission service costs provided by third parties) (2) 10 (12) ($30) $3 ($33) Cost of Gas Sold Expense Variances - The following items contributed to (increased) decreased cost of gas sold expense for 2024 compared to 2023 (in millions): Alliant Energy IPL WPL Lower natural gas prices and lower retail gas volumes $105 $66 $39 Changes in the regulatory recovery of gas costs (Refer to Note 1(g ) ) (30) (24) (6) Other — 1 — $75 $43 $33 Other Operation and Maintenance Expenses Variances - The following items contributed to (increased) decreased other operation and maintenance expenses for 2024 compared to 2023 (in millions): Alliant Energy IPL WPL Restructuring and voluntary employee separation charges in 2024 (excluding payroll taxes) (Refer to Note 12(a) ) ($27) ($13) ($12) ARO charge for steam assets at IPL in 2024 (Refer to Note 13 ) (20) (20) — Lower energy efficiency expense at IPL (mostly offset by lower revenues) 20 20 — Lower generation and energy delivery expenses 11 3 8 Other 15 5 (4) ($1) ($5) ($8) Other Future Considerations - In addition to items discussed in this report, the following key items could impact Alliant Energy’s, IPL’s and WPL’s future financial condition or results of operations: • Financing Plans - Alliant Energy currently expects to issue up to $25 million of common stock in 2025 through its Shareowner Direct Plan.
Electric Transmission Service Expense Variances - The following items contributed to (increased) decreased electric transmission service expense for 2025 compared to 2024 (in millions): Alliant Energy IPL WPL Changes in regulatory recovery for the difference between actual electric transmission service costs and those costs used to determine rates (Refer to Note 1(g) ) $15 $4 $11 Other (primarily due to changes in transmission service costs provided by third parties) (27) (9) (18) ($12) ($5) ($7) Cost of Gas Sold Expense Variances - The following items contributed to (increased) decreased cost of gas sold expense for 2025 compared to 2024 (in millions): Alliant Energy IPL WPL Changes in retail gas volumes and natural gas prices ($43) ($12) ($31) Changes in the regulatory recovery of gas costs (Refer to Note 1(g ) ) 4 5 (1) ($39) ($7) ($32) Other Operation and Maintenance Expenses Variances - The following items contributed to (increased) decreased other operation and maintenance expenses for 2025 compared to 2024 (in millions): Alliant Energy IPL WPL Higher generation and energy delivery expenses ($26) ($8) ($18) Higher incentive compensation expense (20) (11) (9) Asset valuation charge for Alliant Energy’s non-utility business in 2025 (Refer to Note 17) (16) — — Development costs for new generation (14) (6) (8) Higher energy efficiency expense at IPL (mostly offset by higher revenues) (11) (11) — Restructuring and voluntary employee separation charges in 2024 (excluding payroll taxes) (Refer to Note 12(a) ) 27 13 12 ARO charge for steam assets at IPL in 2024 (Refer to Note 13 ) 20 20 — Other (24) (12) (4) ($64) ($15) ($27) 34 Table of Contents Other Future Considerations - In addition to items discussed in this report, the following key items could impact Alliant Energy’s, IPL’s and WPL’s future financial condition or results of operations: • Financing Plans - Alliant Energy currently expects to issue up to $2.4 billion of common stock in aggregate from 2026 through 2029 through the distribution agreement that was executed in May 2025, its Shareholder Direct Plan (up to $25 million in common stock annually) and additional future equity offerings.
CUSTOMER INVESTMENTS Alliant Energy’s, IPL’s and WPL’s strategic priorities include making significant customer-focused investments toward reliable, resilient and sustainable customer energy solutions. These priorities include: Resource Planning Alliant Energy’s current resource plan continues to add resources in Iowa and Wisconsin, and serves as a guide to meet customer demand for affordable, safe, reliable and sustainable energy.
CUSTOMER INVESTMENTS Alliant Energy’s, IPL’s and WPL’s strategic priorities include making significant customer-focused investments toward reliable, resilient and sustainable customer energy solutions. These priorities include: Resource Planning Alliant Energy’s current resource plan guides the addition of resources in Iowa and Wisconsin to meet customer demand for energy solutions that are affordable, safe, reliable, and responsibly delivered.
Alliant Energy’s mission and purpose are supported by a strategy focused on meeting evolving customer expectations, providing an attractive return for investors, and advancing emerging technologies with safe, secure energy production.
Alliant Energy’s mission and purpose are supported by a strategy focused on meeting evolving customer expectations, delivering attractive returns for investors, and advancing emerging technologies and generation to enable safe, secure and future-ready energy production.
Natural Gas-fired Electric Generating Unit - In February 2025, IPL filed request with the IUC for approval to construct, own and operate the Cedar River Generating Station, a 94 MW natural gas-fired EGU using Reciprocating Internal Combustion Engine (RICE) technology, at the site of IPL’s Prairie Creek Generation Station.
New Natural Gas-fired Electric Generation - In June 2025, IPL received approval from the IUC to construct, own and operate the Cedar River Generating Station, a 94 MW natural gas-fired EGU using RICE technology, at the site of IPL’s Prairie Creek Generation Station.
Alliant Energy’s retail gas sales volumes decreased 6% in 2024 compared to 2023, primarily due to changes in temperatures.
Alliant Energy’s retail gas sales volumes increased 14% in 2025 compared to 2024, primarily due to changes in temperatures.
Alliant Energy’s increase was partially offset by decreased sales for resale bulk power and other revenues at IPL primarily due to lower prices for electricity and capacity sold by IPL to MISO wholesale energy markets. These changes were largely offset by changes in fuel-related costs.
(c) Sales for resale bulk power and other revenues increased primarily due to higher prices for electricity and capacity sold by IPL and WPL to MISO wholesale energy markets. These changes were largely offset by changes in electric fuel-related costs.
In July 2024, the U.S. Department of Energy Office of Clean Energy Demonstrations awarded WPL’s Columbia Energy Storage Project, an approximately 20 MW compressed CO2-based long-duration energy storage system at the Columbia 34 Table of C o ntents Energy Center site, up to approximately $30 million in grant funding during construction of the project.
Department of Energy Office of Electricity - formerly administered by the Office of Clean Energy Demonstrations awarded WPL’s Columbia Energy Storage Project, an approximately 20 MW compressed CO2-based long-duration energy storage system at the Columbia Energy Center site, up to approximately $30 million in grant funding during construction of the project. • In April 2025, WPL submitted an application to the U.S.
(b) In December 2023, the PSCW issued an order authorizing an annual base rate increase of $49 million for WPL’s retail electric customers, covering the 2024 forward-looking Test Period, which reflects revenue requirement impacts of increasing electric rate base and lower forecasted fuel-related expenses.
(b) In December 2023, the PSCW issued an order authorizing an annual base rate increase of $60 million for WPL’s retail electric customers, covering the 2025 forward-looking Test Period, which reflects revenue requirement impacts of increasing electric rate base including investments in solar generation and energy storage.
Gas system investments will focus on pipeline replacement to ensure safety and pipeline expansion to support reliability and economic development.
Gas system investments will focus on pipeline replacement to modernize Alliant Energy’s gas distribution systems and pipeline expansion to support reliability and economic development.
“ Customer Investments ” provides details of WPL’s solar generation projects recently completed. 45 Table of C o ntents AROs - The fair value of a legal obligation associated with the retirement of an asset is recorded as a liability when an asset is placed in service, when a legal obligation is subsequently identified or when sufficient information becomes available to determine a reasonable estimate of the fair value of future retirement costs.
AROs - The fair value of a legal obligation associated with the retirement of an asset is recorded as a liability when an asset is placed in service, when a legal obligation is subsequently identified or when sufficient information becomes available to determine a reasonable estimate of the fair value of future retirement costs.

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