ALLIANT ENERGY CORP

Alliant Energy’s, IPL’s and WPL’s strategic priorities include making significant customer-focused investments toward cleaner energy and more reliable, resilient and sustainable customer solutions. These priorities include:

Clean Energy Blueprint

Alliant Energy has developed a Clean Energy Blueprint, or the roadmap for its transition to cleaner energy, as a guide to meet customer demand for affordable, safe, reliable and sustainable energy in Iowa and Wisconsin. This strategy includes the development and acquisition of additional renewable energy, including approximately 1,100 MW of solar generation at WPL with in-service dates in 2022-2024, approximately 275 MW of battery storage at WPL with in-service dates in 2024 and 2025, and approximately 400 MW of solar generation at IPL with in-service dates in 2024. In order to support reliable and sustainable energy and meet MISO’s seasonal resource adequacy requirements, Alliant Energy, IPL and WPL continue to evaluate additional opportunities for renewables and battery storage projects, dispatchable gas generation projects, and distributed energy resources, as well as repowering existing wind farms. Estimated capital expenditures for these planned projects for 2024 through 2027 are included in the “Renewables and battery storage projects” line in the construction and acquisition table in “Liquidity and Capital Resources.”

WPL’s Generation Projects -In 2021 and 2022, WPL received orders from the PSCW for its first and second solar CAs authorizing WPL to acquire, construct, own, and/or operate 675 MW and 414 MW, respectively, of new solar generation in various Wisconsin counties. In 2022 and 2023, 250 MW and 639 MW of solar projects were placed in service, respectively, and a 200 MW solar project is expected to be placed in service in 2024. The 1,089 MW of new solar generation is expected to help replace energy and capacity being eliminated with the planned retirements of the coal-fired Edgewater Generating Station (414 MW) by June 1, 2025, and Columbia Units 1 and 2 (595 MW in aggregate) by June 1, 2026, which are the last coal-fired EGUs at WPL.

In June 2023, WPL filed requests with the PSCW for approval to construct improvements at the natural gas-fired Neenah Energy Facility and Sheboygan Falls Energy Facility, which would increase the capacity and efficiency of the EGUs. A decision from the PSCW is currently expected by the second quarter of 2024.

In August 2023, WPL received an order from the PSCW authorizing WPL to construct, own and operate 175 MW of battery storage, with 100 MW and 75 MW at the Grant County and Wood County solar projects, respectively, which are currently expected to be placed in service in 2024.

In December 2023, WPL received an order from the PSCW authorizing WPL to construct, own and operate approximately 99 MW of battery storage at the Edgewater Generating Station, which is currently expected to be placed in service in 2025.

IPL’s Generation Projects -In October 2023, the IUB issued an order approving a modified non-unanimous settlement agreement with the Iowa Office of Consumer Advocate among other stakeholders, for advance rate-making principles for up to 400 MW of solar generation, subject to a cost target of $1,650/kilowatt, including AFUDC and transmission upgrade costs among other costs, and a related return on common equity of no less than 10.25% with the opportunity to request a higher return on common equity in future IPL retail electric rate review filings. Any reasonable and prudent costs incurred in excess of the cost target are eligible for recovery at the return on common equity determined in IPL retail electric rate review filings. The IUB’s order also included a consumer protection plan, which monitors IPL’s achievement of certain aggregate summer capacity factors for the up to 400 MW of solar generation projects during June, July and August each calendar year over 30 years. Actual three-year rolling average summer capacity factors will be compared to target capacity factors, which may result in surpluses or deficits that would be offset against one another and contribute to an accumulated balance in a given calendar year. Surpluses or deficits will be capped at $3 million in aggregate per year. At the end of the program, any accumulated deficit balance would be addressed in IPL’s next rate review, and any accumulated surplus balance would not result in any return to IPL. In November 2023, IPL accepted these advance rate-making principles.

In 2023, the IUB issued GCU Certificates granting IPL approval to construct, own and operate up to 150 MW of solar generation at the Wever project in Lee County, Iowa and up to 50 MW of solar generation at the Creston project in Union County, Iowa. These solar projects are included in the IUB’s October 2023 order approving advance rate-making principles for up to 400 MW of solar generation. The IUB also issued GCU Certificates granting IPL approval to construct, own and operate up to 100 MW of battery storage (75 MW at the Wever project and 25 MW at the Creston project), which was not included in the IUB’s October 2023 order approving advance rate-making principles, and is subject to future regulatory approval.

The 400 MW of new solar generation would help replace a portion of the energy and capacity eliminated with the May 2023 retirement of the coal-fired Lansing Generating Station (275 MW) and the reduction of energy and capacity resulting from the December 2021 fuel switch of the Burlington Generating Station (212 MW) from coal to natural gas. In addition, IPL’s plans include additional renewables and distributed energy resources, including community solar and small-scale energy storage systems, and repowering existing wind farms, to add energy and capacity.

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)Upon WEC’s exercise of its options, 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 in the next several years. IPL retired the coal-fired Lansing Generating Station (275 MW) in May 2023, and currently expects to fuel switch or retire Prairie Creek Units 1 and 3 (65 MW in aggregate) by December 31, 2025. WPL currently expects to retire the coal-fired Edgewater Generating Station (414 MW) by June 1, 2025, and Columbia Units 1 and 2 (595 MW in aggregate) by June 1, 2026. 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 these EGUs.

Environmental Stewardship -Alliant Energy’s environmental stewardship is focused on meeting its customers’ energy needs affordably, safely, reliably and sustainably. Alliant Energy proactively considers future environmental compliance requirements and proposed regulations in its planning, decision-making, construction and ongoing operations activities. Alliant Energy is focused on executing a long-term strategy to deliver reliable and affordable energy with lower emissions independent of changing policies and political landscape. To achieve these long-term goals, Alliant Energy will transition away from coal-fired EGUs by incorporating renewable energy, distributed energy resources, energy efficiency, demand response, natural gas-fired EGUs and other technologies such as energy storage.

Alliant Energy’s current voluntary environmental-related goals and achievements include the following:

•Exceeded its 2020 targets by reducing air emissions for sulfur dioxide by over 90%, nitrogen oxides by over 80% and mercury by over 90% from 2005 levels.

•By 2030, reduce GHG emissions from its utility operations by 50% from 2005 levels, reduce its electric utility water supply by 75% from 2005 levels and electrify 100% of its owned light-duty fleet vehicles.

•By 2040, eliminate all coal-fired EGUs from its generating fleet and reduce GHG emissions from its utility operations by 80% from 2005 levels.

•By 2050, aspire to achieve net-zero GHG emissions from its utility operations.

Alliant Energy’s aspirational GHG goal includes EPA reportable emissions based on applicable regulatory compliance requirements for CO2, methane and nitrous oxide from its owned fossil-fueled EGUs and distribution of natural gas. In addition, Alliant Energy’s environmental stewardship efforts include a goal to partner to plant more than 1 million trees by the end of 2030. Future updates to sustainable energy plans and attaining these goals will depend on future economic developments, evolving energy technologies and emerging trends in Alliant Energy’s service territories.

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 enabling distributed energy solutions with higher capacity lines. Gas system investments will focus on pipeline replacement to ensure safety and pipeline expansion to support reliability and economic development. Estimated capital expenditures for expected and current electric and gas distribution infrastructure projects for 2024 through 2027 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 is currently installing 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.

Gas Pipeline Safety - The Pipeline and Hazardous Materials Safety Administration published various final rules from 2019 through 2022 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. In anticipation of these rule changes, Alliant Energy, IPL and WPL have been proactively replacing certain of IPL’s transmission pipelines, making modifications to certain of WPL’s transmission pipelines, and updating practices for assessment and operation of these 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, customer self-service and telework. Estimated capital expenditures for expected and current technology projects for 2024 through 2027 are included in the “Other” line in the construction and acquisition expenditures table in “Liquidity and Capital Resources.”

Non-utility business -Alliant Energy continues to explore growth of its Travero businesses and other limited scope opportunities outside of, but complementary to, Alliant Energy’s core utility business. This non-utility strategy continues to evolve through exploration of modest strategic opportunities that are accretive to earnings and cash flows.

RATE MATTERS

Rate Reviews

Retail Base Rate Filings -Base rate changes reflect both returns on additions to infrastructure and recovery of changes in costs incurred or expected to be incurred to provide electric and gas service to retail customers. Given that a portion of the rate changes will offset changes in costs, revenues from rate changes should not be expected to result in an equal change in net income for either IPL or WPL.

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. The PSCW’s order also authorized WPL to implement an additional $60 million increase in annual rates for its retail electric customers, effective January 1, 2025, for the 2025 forward-looking Test Period. The key drivers for the annual base rate increases include revenue requirement impacts of increasing electric and gas rate base, including investments in solar generation and battery storage. 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 PSCW also authorized WPL to defer the incremental under-/over-collection of solar and battery storage renewable tax credits that are outside of the approved amounts. In addition, the PSCW authorized continued recovery of and a return on the remaining net book value of Edgewater Unit 5, which is currently expected to be retired by June 1, 2025. Refer to Note 3 for details of the PSCW’s February 2024 oral decision approving WPL’s deferral request to seek recovery of solar generation construction costs that exceed amounts previously approved by the PSCW in a future regulatory proceeding.

IPL’s Retail Electric and Gas Rate Reviews (October 2024 Through September 2025 Forward-looking Test Period) - In October 2023, IPL filed a retail electric and gas rate review with the IUB for the October 2024 through September 2025 forward-looking Test Period. The key drivers for the filing include revenue requirement impacts of increasing electric and gas rate base, including investments in solar generation and repowering of the existing Franklin County wind farm, as well as certain incremental costs and benefits incurred resulting from the 2020 derecho windstorm. The filing requested approval for IPL to implement increases in annual rates for its retail electric and gas customers of $160 million and $14 million, respectively, with any granted rate changes expected to be effective on October 1, 2024. IPL’s filing also requested approval to implement an additional $124 million increase in annual rates for its retail electric customers in 2025, with any granted rate changes expected to be effective on October 1, 2025. IPL also requested a return on common equity of 10% and a 52% common equity component of its regulatory capital structure, as well as to receive continued recovery of and a return on the remaining net book value of the Lansing Generating Station through 2037, which was retired in May 2023. A decision from the IUB is currently expected in the third quarter of 2024.

WPL’s Retail Fuel-related Rate Filing (2022 Forward-looking Test Period) - In August 2023, the PSCW authorized WPL to collect $117 million in higher rates, plus interest, from its retail electric customers from October 2023 through December 2025 for fuel-related costs incurred by WPL in 2022 that were higher than fuel-related costs used to determine rates for such period.

WPL’s Retail Fuel-related Rate Filing (2023 Forward-looking Test Period) - In December 2022, the PSCW authorized WPL to collect $47 million in higher rates in 2023 from its retail electric customers to reflect an increase in expected fuel-related costs for 2023 compared to WPL’s approved 2022 fuel-related costs.

Rate Review Details - Details related to IPL’s and WPL’s key jurisdictions were as follows:

(a)Authorized returns on common equity may not be indicative of actual returns earned or projections of future returns.

(b)Average rate base amounts reflect IPL’s allocated retail share of rate base and do not include CWIP, and were calculated using a forecasted 13-month average for the test period.

(c)Average rate base amounts recovered through IPL’s renewable energy rider mechanism include construction costs incurred to fund IPL’s 1,000 MW of wind generation facilities placed in service in 2019 and 2020 (11.00% return on common equity), production tax credit carryforwards for the 1,000 MW of wind generation facilities (5.00% return on common equity) and certain transmission facilities classified as intangible assets (9.50% return on common equity), and were calculated using a 13-month average.

(d)Average rate base amounts reflect WPL’s allocated retail share of rate base and do not include CWIP or a cash working capital allowance, and were calculated using a forecasted 13-month average for the test period. The PSCW provides a return on selected CWIP and a cash working capital allowance by adjusting the percentage return on rate base.

LEGISLATIVE MATTERS

In August 2022, the Inflation Reduction Act of 2022 was enacted. The most significant provisions of the new 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 battery storage projects and the right to transfer renewable tax credits generated after 2022 to other corporate taxpayers. 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. Alliant Energy, IPL and WPL are utilizing various provisions of the new legislation to enhance the tax benefits expected from their announced solar and battery storage projects, including transferring the future tax credits from such projects to other corporate taxpayers, as well as the repowering of existing wind farms. The impact of these changes is expected to result in more cost benefits for IPL’s and WPL’s customers, higher rate base amounts, additional financing needs expected to be satisfied with additional long-term debt and common stock issuances, and improvements in long-term cash flows over the life of the solar, battery storage and wind repowering projects. Refer to Note 1(c) for discussion of the transfer of renewable tax credits to other corporate taxpayers in 2023.

Refer to Note 12 for discussion of Iowa tax reform enacted in March 2022.

In November 2021, the Infrastructure Investment and Jobs Act (IIJA Act) was enacted. The most significant provisions of the IIJA Act for Alliant Energy relate to a variety of infrastructure-related priorities, including transportation, environmental, energy and broadband infrastructure. In addition, the IIJA Act is intended to accelerate research, development, demonstration and deployment of carbon-free technologies, including hydrogen and carbon capture and storage.

In March 2021, the American Rescue Plan Act of 2021 (Act) was enacted. The most significant provision of the Act for Alliant Energy is reduced minimum pension plan funding requirements, which Alliant Energy adopted in August 2021. The Act also provides additional funding to the Low Income Home Energy Assistance Program, which assists certain of Alliant Energy’s customers with managing their energy costs, as well as provides financial support for certain of Alliant Energy’s residential, small business and non-profit customers.