ALLIANT ENERGY CORP

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. 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. 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. 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. Refer to Note 3 for discussion of the construction costs associated with these projects.

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.

In July 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. In June 2025, WPL received an order from the PSCW authorizing the construction of the energy storage system. Any grant proceeds are expected to reduce the cost of the project for WPL’s customers.

In February 2025, WPL filed a CA application with the PSCW for approval to construct a 2 billion cubic feet, or 25 million gallon, liquified natural gas facility in Rock County, Wisconsin. A decision from the PSCW is currently expected in the second quarter of 2026.

New Wind - In April 2025, WPL filed a CA application with the PSCW for approval to construct, own and operate the Bent Tree North EGU, an approximately 153 MW wind farm. A decision from the PSCW is currently expected in the second quarter of 2026. In January 2026, WPL filed a CA application with the PSCW for approval to acquire, construct, own and place into service an approximately 277 MW wind farm in Columbia County, Wisconsin. The CA application also included a request for approval of an agreement between WPL and an affiliated subsidiary of AEF, under which WPL would acquire wind development assets from the affiliate. A decision from the PSCW is currently expected in the first quarter of 2027.

New Natural Gas-fired Electric Generation - In April 2025, the PSCW issued an order authorizing WPL to construct, own and operate a 17.5 MW natural gas-fired EGU using Reciprocating Internal Combustion Engine (RICE) technology, at the site of its Riverside Energy Center.

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. In 2025, the Neenah Unit 1 and Sheboygan Falls Unit 1 advanced gas path projects were completed, which increased the efficiency and capacity at each of these EGUs. The Neenah Unit 2 and Sheboygan Falls Unit 2 advanced gas path projects are expected to be completed in the second quarter of 2026.

Existing Wind Farm Refurbishment - In May 2025, the PSCW issued an order authorizing WPL to refurbish the Bent Tree wind farm. In December 2025, the PSCW issued an order authorizing WPL to refurbish the Forward Wind Energy Center.

IPL’s Generation and Energy Storage Projects -

New Solar - In 2024, IPL completed 400 MW of new solar generation projects in Iowa.

New Energy Storage - In 2024, IPL received approval from the IUC to construct, own and operate up to 99 MW of energy storage, which was placed in service in November 2025 at the site of its Wever solar facility. In July 2025, the IUC issued an order authorizing IPL to construct, own and operate up to 150 MW of energy storage at the site of its retired Lansing Generating Station. In August 2025, the IUC issued an order authorizing IPL to construct, own and operate up to 75 MW of energy storage at the site of its Golden Plains wind farm. In September 2025, the IUC issued an order authorizing IPL to construct, own and operate up to 75 MW of energy storage at the site of its Whispering Willow - North wind farm.

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. In December 2025, IPL received an order from the IUC for approval to construct, own and operate an approximately 720 MW simple-cycle natural gas-fired EGU at the site of its Marshalltown Generating Station, known as the Bobcat Energy Center. In January 2026, IPL received approval from the IUC to construct, own and operate a 94 MW natural gas-fired EGU using RICE technology at the site of its Burlington Generating Station.

New Wind - In July 2025, IPL filed for advance rate-making principles with the IUC for up to 1,000 MW of new wind generation in Iowa. The advance rate-making principles filing included requests for a fixed cost cap of $3,020/kilowatt, including AFUDC and transmission upgrade costs among other costs, and a return on common equity of 11.25%. In December 2025, IPL reached a non-unanimous settlement agreement with the Iowa Office of Consumer Advocate and others, subject to IUC approval, for up to 1,000 MW nameplate capacity of wind generation with a cost cap of $3,020/kW including AFUDC and transmission costs. IPL’s return on common equity will be the same as other assets without advance rate-making principles for purposes of setting future rates and IPL’s blended return on common equity, which will be updated each year, will be used for IPL’s retail electric earnings sharing mechanism calculation. A decision from the IUC is currently expected in the first half of 2026.

Existing Wind Farm Refurbishment - In 2024, IPL completed the refurbishment of the existing Franklin County wind farm in Iowa. IPL currently expects the refurbishment of the existing Whispering Willow - East wind farm to be completed in 2026. These projects are eligible for production tax credits under the Inflation Reduction Act of 2022.

WPL’s West Riverside Natural Gas-fired Generating Station -In 2020, WPL completed the construction of West Riverside, a 723 MW natural gas-fired combined-cycle EGU in Beloit, Wisconsin. WPL entered into agreements with neighboring utilities and electric cooperatives that provide each of them options to purchase a partial ownership interest in West Riverside. The purchase price for such options is based on the ownership interest acquired and the net book value of West Riverside on the date of the purchase. The timing and ownership amount of the options are as follows:

(a)WPL may exercise reciprocal options, subject to approval by the PSCW, to purchase up to 200 MW of any natural-gas combined-cycle EGU that WEC places in service prior to May 2030.

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. WPL currently plans to continue coal operations at Edgewater Unit 5 (414 MW) and Columbia Units 1 and 2 (595 MW in aggregate) at least through 2029, as well as evaluate the potential conversion of these EGUs to natural gas. 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.

Environmental Stewardship -Alliant Energy’s environmental stewardship is focused on the implementation of a responsible energy strategy. Alliant Energy’s strategy and business plans consider the transition to a low-carbon economy as one of several factors driving transformation of the energy industry. Alliant Energy’s journey toward carbon reductions includes long-term voluntary goals to eliminate all coal-fired EGUs from its generating fleet by 2040 and aspiring to achieve net-zero GHG emissions from its utility operations by 2050.

Alliant Energy’s voluntary Environmental Stewardship goals previously included interim 2030 environmental-related goals for GHG emissions, utility water supply, and electrifying owned light-duty fleet vehicles. In the first quarter of 2026, Alliant Energy decided to remove the interim 2030 voluntary environmental-related goals while remaining focused on its long-term voluntary goals. This decision was made due to a combination of factors, including the need to serve its customers with affordable, safe, and reliable energy, resource adequacy requirements, and increasing customer energy needs.

Alliant Energy’s voluntary environmental stewardship goals may be revised, or their achievement may be delayed, based on increasing customer energy needs, reliability and resource adequacy requirements, and tax policy changes. The ability to achieve these goals will depend on future economic developments, evolving energy technologies and emerging trends in Alliant Energy’s service territories. These goals are not meant to be considered guidance.

Other Customer-focused Investments

Electric and Gas Distribution Systems -Customer-focused investments include replacing, modernizing and upgrading infrastructure in the electric and gas distribution systems. Electric system investments will focus on areas such as improving reliability and resiliency with more underground electric distribution and upgrades including automation and enabling distributed energy resources. 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. Estimated capital expenditures for expected and current electric and gas distribution infrastructure projects for 2026 through 2029 are included in the “Electric and gas distribution systems” lines in the construction and acquisition expenditures table in “Liquidity and Capital Resources.”

Fiber Optic Telecommunication Network -Alliant Energy installed fiber optic routes between its facilities to enhance its communications network to improve resiliency and reliability of, and enable and strengthen, the integrated grid network focused on less densely populated rural areas.

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. The majority of identified remediation efforts have been completed with remaining items to be completed by July 2035. In response to these rule changes, Alliant Energy, IPL and WPL have been assessing, testing and modifying certain of IPL’s and WPL’s pipelines, and updating practices for assessment and operation of all IPL and WPL pipelines. 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. Estimated capital expenditures for expected and current technology projects for 2026 through 2029 are included in the “Other” line in the construction and acquisition expenditures table in “Liquidity and Capital Resources.”