Pension and Other Postretirement Plans

9 Months Ended

Sep. 30, 2023

Retirement Benefits [Abstract]

Pension and Other Postretirement Plans

5.Pension and Other Postretirement Plans - MGE Energy and MGE.

MGE maintains qualified and nonqualified pension plans, health care, and life insurance benefits and defined contribution 401(k) benefit plans for its employees and retirees.

The components of net periodic benefit cost, other than the service cost component, are recorded in "Other income, net" on the consolidated statements of income. The service cost component is recorded in "Other operations and maintenance" on the consolidated statements of income. MGE has regulatory treatment and recognizes regulatory assets or liabilities for timing differences between when net periodic benefit costs are recovered and when costs are recognized.

The following table presents the components of net periodic benefit costs recognized.

	Three Months Ended						Nine Months Ended
	September 30,						September 30,
(In thousands)	2023			2022			2023			2022
Pension Benefits
Components of net periodic benefit cost:
Service cost	$	723		$	1,266		$	2,169		$	3,798
Interest cost		4,330			2,791			12,989			8,371
Expected return on assets		(6,312	)		(7,848	)		(18,936	)		(23,543	)
Amortization of:
Prior service credit		—			(5	)		—			(15	)
Actuarial loss		440			604			1,320			1,812
Net periodic benefit (credit) cost	$	(819	)	$	(3,192	)	$	(2,458	)	$	(9,577	)
Postretirement Benefits
Components of net periodic benefit cost:
Service cost	$	195		$	323		$	585		$	970
Interest cost		827			485			2,481			1,455
Expected return on assets		(649	)		(842	)		(1,946	)		(2,524	)
Amortization of:
Transition obligation		1			1			2			2
Prior service credit		—			(74	)		—			(223	)
Actuarial (gain) loss		(48	)		37			(143	)		109
Net periodic benefit (credit) cost	$	326		$	(70	)	$	979		$	(211	)

As approved by the PSCW, MGE is allowed to defer differences between actual employee benefit plan costs and costs reflected in current rates. The deferred costs may be recovered or refunded in MGE's next rate filing. During the three and nine months ended September 30, 2023, MGE deferred $1.6 million and $2.4 million, respectively, of pension and other postretirement costs. During the three and nine months ended September 30, 2022, MGE recovered $0.2 million and $0.8 million, respectively, of pension and other postretirement costs previously deferred. These costs have not been reflected in the table above.