ALLIANT ENERGY CORP

NOTE 18. RELATED PARTIES

Service Agreements -Pursuant to service agreements, IPL and WPL receive various administrative and general services from an affiliate, Corporate Services. These services are billed to IPL and WPL at cost based on expenses incurred by Corporate Services for the benefit of IPL and WPL, respectively. These costs consisted primarily of employee compensation and benefits, fees associated with various professional services, depreciation and amortization of property, plant and equipment, and a return on net assets. Corporate Services also acts as agent on behalf of IPL and WPL pursuant to the service agreements. As agent, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions within MISO. Corporate Services assigns such sales and purchases among IPL and WPL based on statements received from MISO. The amounts billed for services provided, sales credited and purchases were as follows (in millions):

As of December 31, net intercompany payables to Corporate Services were as follows (in millions):

ATC -Pursuant to various agreements, WPL receives a range of transmission services from ATC. WPL provides operation, maintenance, and construction services to ATC. WPL and ATC also bill each other for use of shared facilities owned by each party. The related amounts billed between the parties were as follows (in millions):

As of December 31, 2025 and 2024, WPL owed ATC net amounts of $10 million and $10 million, respectively.

WPL’s Sheboygan Falls Energy Facility Lease -Refer to Note 9 for discussion of WPL’s Sheboygan Falls Energy Facility lease.