
	Rate increase	Return on Common Equity	Common Equity Component of Regulatory Capital Structure	Effective Date
Approved 2021 settlement(a)
Electric	—%	9.8%	55.8%	1/1/2021
Gas	4.00%	9.8%	55.8%	1/1/2021
Approved 2022/2023 settlement(b)
Electric	8.81%	9.8%	55.6%	1/1/2022
Gas	2.15%	9.8%	55.6%	1/1/2022
Gas	0.96%	9.8%	55.6%	1/1/2023
Approved limited 2023 reopener(c)
Electric	9.01%	9.8%	55.6%	1/1/2023
Approved 2024/2025 rate proceeding(d)(e)
Electric	1.54%	9.7%	56.1%	1/1/2024
Gas	2.44%	9.7%	56.1%	1/1/2024
Electric	4.17%	9.7%	56.1%	1/1/2025
Gas	1.32%	9.7%	56.1%	1/1/2025

(a)

The electric rate settlement included an increase in rate base but the associated rate increase was primarily offset by lower fuel and purchased power costs and a one-time $18.2 million return to customers of the portion of excess deferred taxes related to the 2017 Tax Act not restricted by IRS normalization rules. The gas rate increase covered infrastructure costs and technology improvements. The settlement agreement also included escrow accounting treatment for pension and other postretirement benefit costs, bad debt expense, and customer credit card fees. Escrow accounting treatment allows MGE to defer any difference between estimated costs in rates and actual costs incurred until a future rate filing. Any difference would be recorded as a regulatory asset or regulatory liability.

(b)

The electric and gas rate increases were driven by an increase in rate base including our investments in Badger Hollow I and a new customer information system. Also driving the requested electric increase were higher fuel and purchased power costs as well as the completion in 2021 of the one-time return of the electric excess deferred tax credit related to the 2017 Tax Act not restricted by IRS normalization rules. Included in the electric residential rate is a reduction in the customer fixed charge.

(c)

The electric rate increase was driven by generation assets including our investments in Badger Hollow II (solar), Paris (solar and battery), Red Barn (wind), and West Riverside (natural gas). In addition, the reopener request included an increase in fuel costs and the recovery of deferred 2021 fuel costs. The reopener also revised the depreciation schedule for Columbia Unit 2 and shared equipment to 2029 to align with the depreciation schedule for Columbia Unit 1.

(d)

The electric increase was driven by an increase in rate base including our investments made in West Riverside, local solar, and continued investment in grid modernization, as well as higher costs for transmission, pension and OPEB, and uncollectible costs (including costs previously deferred from prior years). This increase in electric costs is offset by a decrease in fuel costs and benefit from lower tax expense (including impacts from the Inflation Reduction Act). MGE will file an updated 2025 fuel forecast with the PSCW in 2024 which may impact rates in 2025, depending on any variance between the forecast submitted as part of the rates and updated forecast. In addition, the PSCW authorized MGE to defer a recovery of and a return on costs associated for any change in the in service date for Paris and Darien and force majeure costs for Badger Hollow II, Paris, and Darien that were not reflected in this rate filing. The PSCW also approved deferral of any differential in PTC tax credits reflected in rates and actual credits produced. These deferrals will be reflected in MGE's next rate case filing. The gas rate increases were also driven by our investment made in grid modernization and higher pension and OPEB and uncollectible costs (including costs previously deferred from prior years). This increase in gas costs is offset by a tax benefit related to excess deferred taxes. Included in the gas residential rate is a reduction in the customer fixed charge.

(e)

In accordance with the 2024/2025 rate order from the PSCW, MGE will have an earnings sharing mechanism, under which, if MGE earns above the authorized ROE: (i) the utility will retain 100.0% of earnings for the first 15 basis points above the authorized ROE; (ii) 50.0% of the next 60 basis points will be required to be refunded to ratepayers; and (iii) 100.0% of any remaining excess earnings will be required to be refunded to ratepayers.

Sierra Club and Vote Solar have filed petitions with the Dane County Circuit Court seeking review of the PSCW decisions approving MGE's electric and gas 2022/2023 rate settlement, 2023 electric limited reopener, and 2024/2025 rate order. The PSCW is named as the responding party; MGE is not named as a party. The Petitions challenge the amount of customer fixed charge that does not vary with usage. The requested relief is unclear. The revenue requirement approved by the PSCW in the settlement, the

limited reopener, and 2024/2025 rate order have not been challenged. The PSCW is expected to vigorously defend its approval of the rate case settlement, limited reopener, and the 2024/2025 rate order. MGE has intervened in the proceedings to further defend the PSCW's decisions. The Dane County Circuit Court affirmed the PSCW's decision to approve the 2022/2023 rate settlement, and Sierra Club and Vote Solar have now appealed that decision to the Wisconsin Court of Appeals.

Fuel rules require Wisconsin utilities to defer electric fuel-related costs that fall outside a symmetrical cost tolerance band around the amount approved for a utility in its annual fuel proceedings. Any over- or under-recovery of the actual costs is determined in the following year and is then reflected in future billings to electric retail customers. The fuel rules bandwidth is set at plus or minus 2% in 2023 and 1% in 2022. The electric fuel-related costs are subject to an excess revenues test. Excess revenues are defined as revenues in the year in question that provide MGE with a greater return on common equity than authorized by the PSCW in MGE's latest rate order. The recovery of under-collected electric fuel-related costs would be reduced by the amount that exceeds the excess revenue test. These costs are subject to the PSCW's annual review of fuel costs completed in the year following the deferral. The following table summarizes deferred electric fuel-related savings and costs: