Rate Matters	3 Months Ended
Mar. 31, 2020
Regulated Operations [Abstract]
Rate Matters	Rate Matters - MGE Energy and MGE. a.Rate Proceedings. In December 2018, the PSCW approved a settlement agreement between MGE and intervening parties in the then-pending rate case. The settlement decreased electric rates by 2.24%, or $9.2 million, in 2019. MGE maintained this rate level for 2020, with the exception that MGE's electric rates were adjusted by the 2020 Fuel Cost Plan. The decrease in electric rates reflects the ongoing tax impacts of the Tax Act. Lower fuel costs and an increase in rate base from renewable generation assets further impacted the rate change. In 2020, electric rates decreased 0.84%, or $3.4 million, as approved by the PSCW in December 2019 in the 2020 Fuel Cost Plan. The settlement agreement increased gas rates by 1.06%, or $1.7 million, in 2019 and 1.46%, or $2.4 million, in 2020. The gas increase covers infrastructure costs. It also reflects the impacts of the Tax Act. The return on common stock equity for 2019 and 2020 is 9.8% based on a capital structure consisting of 56.6% common equity in 2019 and 56.1% common equity in 2020. b.Fuel Rules. Fuel rules require the PSCW and 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 currently set at plus or minus 2%. Under fuel rules, MGE would defer costs, less any excess revenues, if its actual electric fuel costs exceeded 102% of the electric fuel costs allowed in its latest rate order. 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. Conversely, MGE is required to defer the benefit of lower costs if actual electric fuel costs were less than 98% of the electric fuel costs allowed in that order. These costs are subject to the PSCW's annual review of fuel costs completed in the year following the deferral. The PSCW issued a final decision in the 2018 fuel rules proceedings for MGE to refund additional fuel savings incurred to its retail electric customers over a one-month period. MGE returned $9.5 million of electric fuel-related savings in October 2019. There was no change to the refund in the fuel rules proceedings from the amount MGE deferred in the previous year. As of March 31, 2020, MGE had no 2020 fuel savings deferred. As of December 31, 2019, MGE had deferred $1.5 million of 2019 fuel savings. These costs will be subject to the PSCW's annual review of 2019 fuel costs, which is expected to be completed in 2020. c.COVID-19. On March 24, 2020, the PSCW issued an order temporarily altering the tariff provisions of all public utilities in Wisconsin. Under the order, MGE: may not disconnect or refuse service to any customer, with limited exceptions; must offer deferred payment agreements for customers unable to pay a bill regardless of customer class; may not charge for late payments; and may not require a cash deposit or other guarantee as a condition of any new service. This order is expected to result in increased expenditures and foregone revenue. However, on March 24, 2020, the PSCW issued an order authorizing deferral of expenditures, late payment charges, and cash deposits necessary to ensure the provision of safe, reliable and affordable access to utility services during the COVID-19 pandemic. As of March 31, 2020, MGE had deferred $0.2 million. Recovery of costs will be addressed in future rate proceedings.

Rate Matters

3 Months Ended

Mar. 31, 2020

Rate Matters - MGE Energy and MGE.

a.Rate Proceedings.

In December 2018, the PSCW approved a settlement agreement between MGE and intervening parties in the then-pending rate case. The settlement decreased electric rates by 2.24%, or $9.2 million, in 2019. MGE maintained this rate level for 2020, with the exception that MGE's electric rates were adjusted by the 2020 Fuel Cost Plan. The decrease in electric rates reflects the ongoing tax impacts of the Tax Act. Lower fuel costs and an increase in rate base from renewable generation assets further impacted the rate change. In 2020, electric rates decreased 0.84%, or $3.4 million, as approved by the

PSCW in December 2019 in the 2020 Fuel Cost Plan. The settlement agreement increased gas rates by 1.06%, or $1.7 million, in 2019 and 1.46%, or $2.4 million, in 2020. The gas increase covers infrastructure costs. It also reflects the impacts of the Tax Act. The return on common stock equity for 2019 and 2020 is 9.8% based on a capital structure consisting of 56.6% common equity in 2019 and 56.1% common equity in 2020.

b.Fuel Rules.

Fuel rules require the PSCW and 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 currently set at plus or minus 2%. Under fuel rules, MGE would defer costs, less any excess revenues, if its actual electric fuel costs exceeded 102% of the electric fuel costs allowed in its latest rate order. 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. Conversely, MGE is required to defer the benefit of lower costs if actual electric fuel costs were less than 98% of the electric fuel costs allowed in that order. These costs are subject to the PSCW's annual review of fuel costs completed in the year following the deferral.

The PSCW issued a final decision in the 2018 fuel rules proceedings for MGE to refund additional fuel savings incurred to its retail electric customers over a one-month period. MGE returned $9.5 million of electric fuel-related savings in October 2019. There was no change to the refund in the fuel rules proceedings from the amount MGE deferred in the previous year.

As of March 31, 2020, MGE had no 2020 fuel savings deferred. As of December 31, 2019, MGE had deferred $1.5 million of 2019 fuel savings. These costs will be subject to the PSCW's annual review of 2019 fuel costs, which is expected to be completed in 2020.

c.COVID-19.

On March 24, 2020, the PSCW issued an order temporarily altering the tariff provisions of all public utilities in Wisconsin. Under the order, MGE: may not disconnect or refuse service to any customer, with limited exceptions; must offer deferred payment agreements for customers unable to pay a bill regardless of customer class; may not charge for late payments; and may not require a cash deposit or other guarantee as a condition of any new service. This order is expected to result in increased expenditures and foregone revenue. However, on March 24, 2020, the PSCW issued an order authorizing deferral of expenditures, late payment charges, and cash deposits necessary to ensure the provision of safe, reliable and affordable access to utility services during the COVID-19 pandemic. As of March 31, 2020, MGE had deferred $0.2 million. Recovery of costs will be addressed in future rate proceedings.