Retirement Plans and Postretirement Benefit Plans

12 Months Ended

Dec. 31, 2023

Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]

Retirement Plans and Postretirement Benefit Plans

11. Retirement Plans and Postretirement Benefit Plans

OGE Energy sponsors defined benefit pension plans, 401(k) savings plans and other postretirement plans covering certain employees of the Registrants.

Pension Plan and Restoration of Retirement Income Plan

OGE Energy periodically makes contributions to the Pension Plan considering information such as net periodic pension expense and funded status from OGE Energy's actuarial consultants. Such contributions are intended to provide not only for benefits attributed to service to date but also for those expected to be earned in the future. OGE Energy did not make a contribution to its Pension Plan during 2023 and 2022 but does expect to make a $10.0 million contribution to its Pension Plan in 2024. Any additional contribution to the Pension Plan during 2024 would be a discretionary contribution, anticipated to be in the form of cash, and is not required to satisfy the minimum regulatory funding requirement specified by the Employee Retirement Income Security Act of 1974, as amended. OGE Energy could be required to make additional contributions if the value of its pension trust and postretirement benefit plan trust assets are adversely impacted by a major market disruption in the future.

In accordance with ASC Topic 715, "Compensation - Retirement Benefits," a one-time settlement charge is required to be recorded by an organization when lump sum payments or other settlements that relieve the organization from the responsibility for the pension benefit obligation during the plan year exceed the service cost and interest cost components of the organization's net periodic pension cost. During 2023, 2022 and 2021, the Registrants experienced an increase in both the number of employees electing to retire and the amount of lump sum payments paid to such employees upon retirement, which resulted in the Registrants recording pension plan settlement charges as presented in the Pension Plan net periodic benefit cost tables below. The pension settlement charges did not require a cash outlay by the Registrants and did not increase total pension expense over time, as the charges were an acceleration of costs that otherwise would be recognized as pension expense in future periods.

OGE Energy provides a Restoration of Retirement Income Plan to those participants in OGE Energy's Pension Plan whose benefits are subject to certain limitations of the Code. Participants in the Restoration of Retirement Income Plan receive the same benefits that they would have received under OGE Energy's Pension Plan in the absence of limitations imposed by the federal tax laws. The Restoration of Retirement Income Plan is intended to be an unfunded plan.

OG&E's employees participate in OGE Energy's Pension Plan and Restoration of Retirement Income Plan.

Obligations and Funded Status

The details of the funded status of OGE Energy's Pension Plan, the Restoration of Retirement Income Plan and the postretirement benefit plans and the amounts included in the balance sheets for 2023 and 2022 are included in the following tables. These amounts have been recorded in Accrued Benefit Obligations with the offset in Accumulated Other Comprehensive Loss (except OG&E's portion, which is recorded as a regulatory asset as discussed in Note 1) in the balance sheets. The amounts in Accumulated Other Comprehensive Loss and those recorded as a regulatory asset represent a net periodic benefit cost to be recognized in the statements of income in future periods. The benefit obligation for OGE Energy's Pension Plan and the Restoration of Retirement Income Plan represents the projected benefit obligation, while the benefit obligation for the postretirement benefit plans represents the accumulated postretirement benefit obligation. The accumulated postretirement benefit obligation for OGE Energy's Pension Plan and Restoration of Retirement Income Plan differs from the projected benefit obligation in that the former includes no assumption about future compensation levels.

	OGE Energy												OG&E
	Pension Plan						Restoration of Retirement Income Plan						Pension Plan						Restoration of Retirement Income Plan
December 31 (In millions)	2023			2022			2023			2022			2023			2022			2023			2022
Change in benefit obligation
Beginning obligations	$	358.5		$	502.9		$	5.8		$	5.9		$	288.5		$	363.2		$	0.5		$	0.5
Service cost		5.4			7.6			1.0			1.1			4.4			6.2			—			—
Interest cost		15.9			15.7			0.3			0.2			12.6			12.1			—			—
Plan settlements		(62.8	)		(95.8	)		(1.4	)		(1.5	)		(57.7	)		(38.8	)		(0.7	)		—
Actuarial losses (gains)		0.8			(56.9	)		(0.2	)		0.1			2.7			(41.3	)		0.2			—
Benefits paid		(14.1	)		(15.0	)		—			—			(11.9	)		(12.9	)		—			—
Ending obligations	$	303.7		$	358.5		$	5.5		$	5.8		$	238.6		$	288.5		$	—		$	0.5
Change in plans' assets
Beginning fair value	$	293.0		$	486.0		$	—		$	—		$	238.9		$	353.0		$	—		$	—
Actual return on plans' assets		27.6			(82.2	)		—			—			22.1			(62.4	)		—			—
Employer contributions		—			—			1.4			0.2			—			—			0.7			—
Plan settlements		(62.8	)		(95.8	)		(1.4	)		(0.2	)		(57.7	)		(38.8	)		(0.7	)		—
Benefits paid		(14.1	)		(15.0	)		—			—			(11.9	)		(12.9	)		—			—
Ending fair value	$	243.7		$	293.0		$	—		$	—		$	191.4		$	238.9		$	—		$	—
Funded status at end of year	$	(60.0	)	$	(65.5	)	$	(5.5	)	$	(5.8	)	$	(47.2	)	$	(49.6	)	$	—		$	(0.5	)
Accumulated postretirement benefit obligation	$	289.5		$	342.7		$	4.9		$	4.8		$	226.5		$	275.2		$	—		$	0.4

For the year ended December 31, 2023, actuarial losses were primarily due to more lump sum payouts than expected, partially offset by demographic experience. For the year ended December 31, 2022, Pension Plan actuarial gains were primarily due to significantly higher discount rates, partially offset by demographic experience and a larger than expected amount of early 2023 lump sum payouts.

	OGE Energy						OG&E
	Postretirement Benefit Plans						Postretirement Benefit Plans
December 31 (In millions)	2023			2022			2023			2022
Change in benefit obligation
Beginning obligations	$	101.9		$	137.3		$	76.4		$	102.4
Service cost		0.1			0.2			0.1			0.1
Interest cost		5.2			3.5			3.9			2.7
Participants' contributions		3.4			3.5			2.4			2.4
Actuarial losses (gains)		4.9			(29.1	)		4.0			(21.0	)
Benefits paid		(12.2	)		(13.5	)		(9.5	)		(10.2	)
Ending obligations	$	103.3		$	101.9		$	77.3		$	76.4
Change in plans' assets
Beginning fair value	$	32.8		$	44.3		$	29.8		$	39.9
Actual return on plans' assets		1.9			(8.2	)		1.7			(7.4	)
Employer contributions		6.8			6.7			5.2			5.1
Participants' contributions		3.4			3.5			2.4			2.4
Benefits paid		(12.2	)		(13.5	)		(9.5	)		(10.2	)
Ending fair value	$	32.7		$	32.8		$	29.6		$	29.8
Funded status at end of year	$	(70.6	)	$	(69.1	)	$	(47.7	)	$	(46.6	)

Net Periodic Benefit Cost

The following tables present the net periodic benefit cost components, before consideration of capitalized amounts, of OGE Energy's Pension Plan, Restoration of Retirement Income Plan and postretirement benefit plans that are included in the financial statements. Service cost is presented within Other Operation and Maintenance Expense, and the remaining net periodic benefit cost components as listed in the following tables are presented within Other Net Periodic Benefit Income (Expense) in the statements of income. OG&E recovers specific amounts of pension and postretirement medical costs in rates approved in its Oklahoma rate reviews. In accordance with approved orders, OG&E defers the difference between actual pension and postretirement medical expenses and the amount approved in its last Oklahoma rate review as a regulatory asset or regulatory liability. These amounts have been recorded in the Pension tracker in the regulatory assets and liabilities table in Note 1 and within Other Net Periodic Benefit Income (Expense) in the statements of income.

OGE Energy	Pension Plan									Restoration of Retirement Income Plan
Year Ended December 31 (In millions)	2023			2022			2021			2023		2022		2021
Service cost	$	5.4		$	7.6		$	11.2		$	1.0	$	1.1	$	0.8
Interest cost		15.9			15.7			13.3			0.3		0.2		0.1
Expected return on plan assets		(16.2	)		(25.4	)		(34.1	)		—		—		—
Amortization of net loss		8.0			8.9			9.4			—		0.2		0.2
Amortization of unrecognized prior service cost (A)		—			—			—			0.3		0.2		0.1
Settlement cost		21.8			30.6			41.3			0.5		0.3		2.1
Total net periodic benefit cost		34.9			37.4			41.1			2.1		2.0		3.3
Less: Amount paid by unconsolidated affiliates		—			—			(0.2	)		—		—		0.1
Net periodic benefit cost	$	34.9		$	37.4		$	41.3		$	2.1	$	2.0	$	3.2

(A)Unamortized prior service cost is amortized on a straight-line basis over the average remaining service period to the first eligibility age of participants who are expected to receive a benefit and are active at the date of the plan amendment.

OG&E	Pension Plan									Restoration of Retirement Income Plan
Year Ended December 31 (In millions)	2023			2022			2021			2023		2022		2021
Service cost	$	4.4		$	6.2		$	7.7		$	—	$	—	$	—
Interest cost		12.6			12.1			9.7			—		—		—
Expected return on plan assets		(12.9	)		(19.6	)		(24.7	)		—		—		—
Amortization of net loss		6.9			7.4			7.0			—		—		0.1
Settlement cost		20.4			12.9			33.1			0.4		—		1.6
Total net periodic benefit cost		31.4			19.0			32.8			0.4		—		1.7
Plus: Amount allocated from OGE Energy		3.0			5.2			6.5			1.7		1.5		1.5
Net periodic benefit cost	$	34.4		$	24.2		$	39.3		$	2.1	$	1.5	$	3.2

In addition to the net periodic benefit cost amounts recognized, as presented in the table above, for the Pension and Restoration of Retirement Income Plans in 2023, 2022 and 2021, the Registrants recognized the following:

Year Ended December 31 (In millions)	2023		2022		2021
Change in pension expense to maintain allowed recoverable amount in Oklahoma jurisdiction (A)	$	33.3	$	15.2	$	23.0
Deferral of pension expense related to pension settlement charges included in the above line item:
Oklahoma jurisdiction (A)	$	20.1	$	15.4	$	37.9
Arkansas jurisdiction (A)	$	1.9	$	1.4	$	3.5

(A)Included in the pension regulatory asset in each jurisdiction, as indicated in the regulatory assets and liabilities table in Note 1.

	OGE Energy									OG&E
	Postretirement Benefit Plans									Postretirement Benefit Plans
Year Ended December 31 (In millions)	2023			2022			2021			2023			2022			2021
Service cost	$	0.1		$	0.2		$	0.2		$	0.1		$	0.1		$	0.1
Interest cost		5.2			3.5			3.4			3.9			2.7			2.6
Expected return on plan assets		(1.7	)		(1.8	)		(1.8	)		(1.6	)		(1.6	)		(1.7	)
Amortization of net loss		(0.2	)		1.5			2.8			—			1.5			2.7
Amortization of unrecognized prior service cost (A)		—			(3.8	)		(6.9	)		—			(3.6	)		(5.0	)
Total net periodic benefit cost (income)		3.4			(0.4	)		(2.3	)		2.4			(0.9	)		(1.3	)
Less: Amount paid by unconsolidated affiliates (B)		—			—			(0.5	)
Plus: Amount allocated from OGE Energy (B)											0.5			—			(0.5	)
Net periodic benefit cost (income)	$	3.4		$	(0.4	)	$	(1.8	)	$	2.9		$	(0.9	)	$	(1.8	)

(A)Unamortized prior service cost is amortized on a straight-line basis over the average remaining service period to the first eligibility age of participants who are expected to receive a benefit and are active at the date of the plan amendment.

(B)"Amount paid by unconsolidated affiliates" is only applicable to OGE Energy. "Amount allocated from OGE Energy" is only applicable to OG&E.

In addition to the net periodic benefit cost or income amounts recognized, as presented in the table above, for the postretirement benefit plans in 2023, 2022 and 2021, the Registrants recognized the following:

Year Ended December 31 (In millions)	2023		2022		2021
Change in postretirement expense to maintain allowed recoverable amount in Oklahoma jurisdiction (A)	$	4.4	$	0.6	$	(0.4	)

(A)Included in the pension regulatory asset, as indicated in the regulatory assets and liabilities table in Note 1.

The following table presents the amount of net periodic benefit cost capitalized and attributable to each of the Registrants for OGE Energy's Pension Plan and postretirement benefit plans in 2023, 2022 and 2021.

	OGE Energy						OG&E
(In millions)	2023		2022		2021		2023		2022		2021
Capitalized portion of net periodic pension benefit cost	$	2.2	$	3.0	$	3.4	$	1.9	$	2.5	$	2.9
Capitalized portion of net periodic postretirement benefit cost	$	0.1	$	0.2	$	0.2	$	0.1	$	0.1	$	0.1

Rate Assumptions

	Pension Plan and Restoration of Retirement Income Plan									Postretirement Benefit Plans
Year Ended December 31	2023			2022			2021			2023			2022			2021
Assumptions to determine benefit obligations:
Discount rate		5.40	%		5.45	%		2.75	%		5.35	%		5.40	%		2.80	%
Rate of compensation increase		4.20	%		4.20	%		4.20	%	N/A			N/A			N/A
Interest crediting rate		3.50	%		3.50	%		3.50	%	N/A			N/A			N/A
Assumptions to determine net periodic benefit cost:
Discount rate		5.45	%		4.01	%		2.63	%		5.40	%		2.80	%		2.45	%
Expected return on plan assets		7.00	%		7.00	%		7.00	%		4.00	%		4.00	%		4.00	%
Rate of compensation increase		4.20	%		4.20	%		4.20	%	N/A			N/A			N/A
Interest crediting rate		3.50	%		3.50	%		3.50	%	N/A			N/A			N/A

N/A - not applicable

The discount rate used to compute the present value of plan liabilities is based generally on rates of high-grade corporate bonds with maturities similar to the average period over which benefits will be paid. The discount rate used to determine net benefit cost for the current year is the same discount rate used to determine the benefit obligation as of the previous year's balance sheet date, unless a plan settlement occurs during the current year that requires an updated discount rate for net periodic cost measurement. For 2023 and 2022, the Pension Plan discount rates used to determine net periodic benefit cost are disclosed on a weighted-average basis.

The overall expected rate of return on plan assets assumption is used in determining net periodic benefit cost. The rate of return on plan assets assumption is the average long-term rate of earnings expected on the funds currently invested and to be invested for the purpose of providing benefits specified by the Pension Plan or postretirement benefit plans. This assumption is reexamined at least annually and updated as necessary. The rate of return on plan assets assumption reflects a combination of historical return analysis, forward-looking return expectations and the plans' current and expected asset allocation.

The assumed health care cost trend rates have a significant effect on the amounts reported for postretirement medical benefit plans. Future health care cost trend rates are assumed to be 6.75 percent in 2024 with the rates trending downward to 4.50 percent by 2033.

Pension Plan

Pension Plan Investments, Policies and Strategies

The Pension Plan assets are held in a trust which follows an investment policy and strategy designed to reduce the funded status volatility of the Plan by utilizing liability driven investing. The purpose of liability-driven investing is to structure the asset portfolio to more closely resemble the pension liability and thereby more effectively hedge against changes in the liability. The investment policy follows a glide path approach that shifts a higher portfolio weighting to fixed income as the Plan's funded status increases. The following table presents the targeted fixed income and equity allocations at different funded status levels.

Projected Benefit Obligation Funded Status Thresholds	<90%	95%	100%	105%	110%	115%	120%
Fixed income	50%	58%	65%	73%	80%	85%	90%
Equity	50%	42%	35%	27%	20%	15%	10%
Total	100%	100%	100%	100%	100%	100%	100%

Within the portfolio's overall allocation to equities, the funds are allocated according to the guidelines in the following table.

Asset Class	Target Allocation	Minimum	Maximum
Domestic Large Cap Equity	40%	35%	60%
Domestic Mid-Cap Equity	15%	5%	25%
Domestic Small-Cap Equity	25%	5%	30%
International Equity	20%	10%	30%

OGE Energy has retained an investment consultant responsible for the general investment oversight, analysis, monitoring investment guideline compliance and providing quarterly reports to certain of the Registrants' members and OGE Energy's Investment Committee. The various investment managers used by the trust operate within the general operating objectives as established in the investment policy and within the specific guidelines established for each investment manager's respective portfolio.

The portfolio is rebalanced at least on an annual basis to bring the asset allocations of various managers in line with the target asset allocation listed above. More frequent rebalancing may occur if there are dramatic price movements in the financial markets which may cause the trust's exposure to any asset class to exceed or fall below the established allowable guidelines.

To evaluate the progress of the portfolio, investment performance is reviewed quarterly. It is, however, expected that performance goals will be met over a full market cycle, normally defined as a three- to five-year period. Analysis of performance is within the context of the prevailing investment environment and the advisors' investment style. The goal of the trust is to provide a rate of return consistently from three percent to five percent over the rate of inflation (as measured by the national Consumer Price Index) on a fee adjusted basis over a typical market cycle of no less than three years and no more than five years. Each investment manager is expected to outperform its respective benchmark.

The following table presents a list of each asset class utilized with appropriate comparative benchmark(s) each manager is evaluated against and the focus of the asset class.

Asset Class	Comparative Benchmark(s)	Focus of Asset Class
Active Duration Fixed Income (A)(B)	Bloomberg Barclays Aggregate	- Maximize risk-adjusted performance while providing long bond exposure managed according to the manager's forecast on interest rates. - All invested assets must reach at or above Baa3 or BBB- investment grade. - Limited five percent exposure to any single issuer, except the U.S. Government or affiliates.
Long Duration Fixed Income (A)(B)	Duration blended Barclays Long Government/Credit & Barclays Universal	- Maximize risk-adjusted performance. - At least 75 percent of invested assets must reach at or above Baaa3 or BBB- investment grade. - Limited five percent exposure to any single issuer, except the U.S. Government or affiliates. - May invest up to 10 percent of the market value in convertible bonds as long as quality guidelines are met. - May invest up to 15 percent of the market value in private placement, including 144A securities with or without registration rights and allow for futures to be traded in the portfolio.
Equity Index (B)(C)	Standard & Poor's 500 Index	- Focus on replicating the performance of the S&P 500 Index.
Mid-Cap Equity (B)(C) Small-Cap Equity (B)(C)	Russell Midcap Index Russell Midcap Value Index Russell 2000 Index Russell 2000 Value Index	- Focus on undervalued stocks expected to earn average return and pay out higher than average dividends. - Invest in companies with market capitalizations lower than average company on public exchanges:       - Price/earnings ratio at or near referenced       - Small dividend yield and return on equity at or near referenced index; and       - Earnings per share growth rate at or near referenced index.
International Equity (D)	Morgan Stanley Capital International ACWI ex-U.S.	- Invest in non-dollar denominated equity securities. - Diversify the overall trust investments.

(A)Investment grades are by Moody's Investors Service, S&P Global Ratings or Fitch Ratings.

(B)The purchase of any of OGE Energy's equity, debt or other securities is prohibited.

(C)No more than five percent can be invested in any one stock at the time of purchase and no more than 10 percent after accounting for price appreciation. Options or financial futures may not be purchased unless prior approval from OGE Energy's Investment Committee is received. The purchase of securities on margin, securities lending, private placement purchases and venture capital purchases are prohibited. The aggregate positions in any company may not exceed one percent of the fair market value of its outstanding stock.

(D)The manager of this asset class is required to operate under certain restrictions including regional constraints, diversification requirements and percentage of U.S. securities. All securities are freely traded on a recognized stock exchange, and there are no over-the-counter derivatives. The following investment categories are excluded: options (other than traded currency options), commodities, futures (other than currency futures or currency hedging), short sales/margin purchases, private placements, unlisted securities and real estate (but not real estate shares).

Pension Plan Investments

The following tables present the Pension Plan's investments that are measured at fair value on a recurring basis at December 31, 2023 and 2022. There were no Level 3 investments held by the Pension Plan at December 31, 2023 and 2022.

(In millions)	December 31, 2023			Level 1		Level 2		Net Asset Value (A)
Common stocks	$	56.9		$	56.9	$	—	$	—
U.S. Treasury notes and bonds (B)		42.4			42.4		—		—
Mortgage- and asset-backed securities		22.0			—		22.0		—
Corporate fixed income and other securities		54.6			—		54.6		—
Commingled fund (C)		13.8			—		—		13.8
Foreign government bonds		0.2			—		0.2		—
U.S. municipal bonds		0.3			—		0.3		—
Money market fund		1.3			—		—		1.3
Mutual funds		55.3			55.3		—		—
Preferred stocks		1.0			1.0		—		—
U.S. Treasury futures:
Cash collateral		0.3			0.3		—		—
Forward contracts:
Receivable (foreign currency)		0.1			—		0.1		—
Total Pension Plan investments		248.2		$	155.9	$	77.2	$	15.1
Interest and dividends receivable		1.4
Receivable from broker for securities sold		8.3
Payable to broker for securities purchased		(14.2	)
Total OGE Energy Pension Plan assets	$	243.7
Pension Plan investments attributable to affiliates		(52.3	)
Total OG&E Pension Plan assets	$	191.4

(In millions)	December 31, 2022			Level 1		Level 2		Net Asset Value (A)
Common stocks	$	71.9		$	71.9	$	—	$	—
U.S. Treasury notes and bonds (B)		44.6			44.6		—		—
Mortgage- and asset-backed securities		26.2			—		26.2		—
Corporate fixed income and other securities		65.5			—		65.5		—
Commingled fund (C)		18.2			—		—		18.2
Foreign government bonds		0.5			—		0.5		—
U.S. municipal bonds		0.9			—		0.9		—
Money market fund		5.9			—		—		5.9
Mutual fund		60.4			60.4		—		—
Preferred stocks		1.5			1.5		—		—
U.S. Treasury futures:
Cash collateral		0.3			0.3		—		—
Forward contracts:
Receivable (foreign currency)		0.1			—		0.1		—
Total Pension Plan investments		296.0		$	178.7	$	93.2	$	24.1
Interest and dividends receivable		1.6
Receivable from broker for securities sold		20.6
Payable to broker for securities purchased		(25.2	)
Total OGE Energy Pension Plan assets	$	293.0
Pension Plan investments attributable to affiliates		(54.1	)
Total OG&E Pension Plan assets	$	238.9

(A)GAAP allows the measurement of certain investments that do not have a readily determinable fair value at the net asset value. These investments do not consider the observability of inputs; therefore, they are not included within the fair value hierarchy.

(B)This category represents U.S. Treasury notes and bonds with a Moody's Investors Service rating of Aaa and Government Agency Bonds with a Moody's Investors Service rating of A1 or higher.

(C)This category represents units of participation in a commingled fund that primarily invested in stocks of international companies and emerging markets.

As defined in the fair value hierarchy, Level 1 inputs are quoted prices in active markets for identical unrestricted assets or liabilities that are accessible by the Pension Plan at the measurement date. Level 2 inputs are inputs other than quoted prices in active markets included within Level 1 that are either directly or indirectly observable at the reporting date for the asset or liability for substantially the full term of the asset or liability. Level 2 inputs include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active. Level 3 inputs are prices or valuation techniques for the asset or liability that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity). Unobservable inputs reflect the Plan's own assumptions about the assumptions that market participants would use in pricing the asset or liability (including assumptions about risk).

Expected Benefit Payments

The following table presents the benefit payments the Registrants expect to pay related to the Pension Plan and Restoration of Retirement Income Plan. These expected benefits are based on the same assumptions used to measure OGE Energy's benefit obligation at the end of the year and include benefits attributable to estimated future employee service.

(In millions)	OGE Energy		OG&E
2024	$	44.4	$	35.4
2025	$	28.1	$	22.2
2026	$	27.9	$	22.4
2027	$	34.2	$	21.1
2028	$	28.0	$	21.0
2029-2033	$	122.7	$	96.3

Postretirement Benefit Plans

In addition to providing pension benefits, OGE Energy provides certain medical and life insurance benefits for eligible retired members. Regular, full-time, active employees hired prior to February 1, 2000 whose age and years of credited service total or exceed 80 or have attained at least age 55 with 10 or more years of service at the time of retirement are entitled to postretirement medical benefits, while employees hired on or after February 1, 2000 are not entitled to postretirement medical benefits. Eligible retirees must contribute such amount as OGE Energy specifies from time to time toward the cost of coverage for postretirement benefits. The benefits are subject to deductibles, co-payment provisions and other limitations. OG&E charges postretirement benefit costs to expense and includes an annual amount as a component of the cost-of-service in future ratemaking proceedings.

OGE Energy's contribution to the medical costs for pre-65 aged eligible retirees are fixed at the 2011 level, and OGE Energy covers future annual medical inflationary cost increases up to five percent. Increases in excess of five percent annually are covered by the pre-65 aged retiree in the form of premium increases. OGE Energy provides Medicare-eligible retirees and their Medicare-eligible spouses an annual fixed contribution to an OGE Energy-sponsored health reimbursement arrangement. Medicare-eligible retirees are able to purchase individual insurance policies supplemental to Medicare through a third-party administrator and use their health reimbursement arrangement funds for reimbursement of medical premiums and other eligible medical expenses.

Postretirement Plans Investments

The following tables present the postretirement benefit plans' investments that are measured at fair value on a recurring basis at December 31, 2023 and 2022. There were no Level 2 investments held by the postretirement benefit plans at December 31, 2023 and 2022.

(In millions)	December 31, 2023			Level 1		Level 3
Group retiree medical insurance contract	$	16.8		$	—	$	16.8
Mutual funds		15.9			15.9		—
Total OGE Energy plan investments	$	32.7		$	15.9	$	16.8
Plan investments attributable to affiliates		(3.1	)
Total OG&E plan investments	$	29.6

(In millions)	December 31, 2022			Level 1		Level 3
Group retiree medical insurance contract	$	21.6		$	—	$	21.6
Mutual funds		11.2			11.2		—
Total OGE Energy plan investments	$	32.8		$	11.2	$	21.6
Plan investments attributable to affiliates		(3.0	)
Total OG&E plan investments	$	29.8

The group retiree medical insurance contract invests in a pool of common stocks, bonds and money market accounts, of which a significant portion is comprised of mortgage-backed securities. The unobservable input included in the valuation of the contract includes the approach for determining the allocation of the postretirement benefit plans' pro-rata share of the total assets in the contract.

The following table presents a reconciliation of the postretirement benefit plans' investments that are measured at fair value on a recurring basis using significant unobservable inputs (Level 3).

Year Ended December 31 (In millions)	2023
Group retiree medical insurance contract:
Beginning balance	$	21.6
Claims paid		(4.5	)
Realized losses		(0.9	)
Investment fees		(0.1	)
Interest income		0.7
Ending balance	$	16.8

Medicare Prescription Drug, Improvement and Modernization Act of 2003

The Medicare Prescription Drug, Improvement and Modernization Act of 2003 expanded coverage for prescription drugs. The following table presents the gross benefit payments the Registrants expect to pay related to the postretirement benefit plans, including prescription drug benefits.

(In millions)	OGE Energy		OG&E
2024	$	13.9	$	10.5
2025	$	11.5	$	8.6
2026	$	10.9	$	8.0
2027	$	9.9	$	7.4
2028	$	9.0	$	6.8
2029-2033	$	36.9	$	27.8

Post-Employment Benefit Plan

Disabled employees receiving benefits from OGE Energy's Group Long-Term Disability Plan are entitled to continue participating in OGE Energy's Medical Plan along with their dependents. The post-employment benefit obligation represents the actuarial present

value of estimated future medical benefits that are attributed to employee service rendered prior to the date as of which such information is presented. The obligation also includes future medical benefits expected to be paid to current employees participating in the Group Long-Term Disability Plan and their dependents, as defined in OGE Energy's Medical Plan.

The post-employment benefit obligation is determined by an actuary on a basis similar to the accumulated postretirement benefit obligation. The estimated future medical benefits are projected to grow with expected future medical cost trend rates and are discounted for interest at the discount rate and for the probability that the participant will discontinue receiving benefits from OGE Energy's Group Long-Term Disability Plan due to death, recovery from disability or eligibility for retiree medical benefits. OGE Energy's post-employment benefit obligation was $1.7 million and $1.8 million at December 31, 2023 and 2022, respectively, of which $1.3 million and $1.3 million, respectively, was OG&E's portion of the obligation.

401(k) Plan

OGE Energy provides a 401(k) Plan, and each regular full-time employee of OGE Energy or a participating affiliate is eligible to participate in the 401(k) Plan immediately upon hire. All other employees of OGE Energy or a participating affiliate are eligible to become participants in the 401(k) Plan after completing one year of service as defined in the 401(k) Plan. Participants may contribute each pay period any whole percentage between two percent and 75 percent of their compensation, as defined in the 401(k) Plan, for that pay period. Participants who have reached age 50 before the close of a year are allowed to make additional contributions referred to as "Catch-Up Contributions," subject to certain limitations of the Code. Participants may designate, at their discretion, all or any portion of their contributions as: (i) a before-tax contribution under Section 401(k) of the Code subject to the limitations thereof, (ii) a contribution made on a non-Roth after-tax basis or (iii) a Roth contribution. The 401(k) Plan also includes an eligible automatic contribution arrangement and provides for a qualified default investment alternative consistent with the U.S. Department of Labor regulations. Participants may elect, in accordance with the 401(k) Plan procedures, to have their future salary deferral rate to be automatically increased annually on a date and in an amount as specified by the participant in such election. For employees hired or rehired on or after December 1, 2009, OGE Energy contributes to the 401(k) Plan, on behalf of each participant, 200 percent of the participant's contributions up to five percent of compensation.

No OGE Energy contributions are made with respect to a participant's Catch-Up Contributions, rollover contributions or with respect to a participant's contributions based on overtime payments, pay-in-lieu of overtime for exempt personnel, special lump-sum recognition awards and lump-sum merit awards included in compensation for determining the amount of participant contributions. Once made, OGE Energy's contribution may be directed to any available investment option in the 401(k) Plan. OGE Energy match contributions vest over a three-year period. After two years of service, participants become 20 percent vested in their OGE Energy contribution account and become fully vested on completing three years of service. In addition, participants fully vest when they are eligible for normal or early retirement under the Pension Plan requirements, in the event of their termination due to death or permanent disability or upon attainment of age 65 while employed by OGE Energy or its affiliates. OGE Energy contributed $19.6 million, $17.1 million and $15.4 million in 2023, 2022 and 2021, respectively, to the 401(k) Plan, of which $16.0 million, $13.9 million and $12.0 million, respectively, related to OG&E.

Deferred Compensation Plan

OGE Energy provides a nonqualified deferred compensation plan which is intended to be an unfunded plan. The plan's primary purpose is to provide a tax-deferred capital accumulation vehicle for a select group of management, highly compensated employees and non-employee members of OGE Energy's Board of Directors and to supplement such employees' 401(k) Plan contributions as well as offering this plan to be competitive in the marketplace.

Eligible employees who enroll in the plan have the following deferral options: (i) eligible employees may elect to defer up to a maximum of 70 percent of base salary and 100 percent of annual bonus awards or (ii) eligible employees may elect a deferral percentage of base salary and bonus awards based on the deferral percentage elected for a year under the 401(k) Plan with such deferrals to start when maximum deferrals to the qualified 401(k) Plan have been made because of limitations in that plan. Eligible directors who enroll in the plan may elect to defer up to a maximum of 100 percent of directors' meeting fees and annual retainers. OGE Energy matches employee (but not non-employee director) deferrals to make up for any match lost in the 401(k) Plan because of deferrals to the deferred compensation plan and to allow for a match that would have been made under the 401(k) Plan on that portion of either the first six percent of total compensation or the first five percent of total compensation, depending on prior participant elections, deferred that exceeds the limits allowed in the 401(k) Plan. Matching credits vest based on years of service, with full vesting after three years or, if earlier, on retirement, disability, death, a change in control of OGE Energy or termination of the

plan. Deferrals, plus any OGE Energy match, are credited to a recordkeeping account in the participant's name. Earnings on the deferrals are indexed to the assumed investment funds selected by the participant. In 2023, those investment options included an OGE Energy Common Stock fund, whose value was determined based on the stock price of OGE Energy's Common Stock. OGE Energy accounts for the contributions related to its executive officers in this plan as Accrued Benefit Obligations and accounts for the contributions related to OGE Energy's directors in this plan as Other Deferred Credits and Other Liabilities in the balance sheets. The investment associated with these contributions is accounted for as Other Property and Investments in the balance sheets. The appreciation of these investments is accounted for as Other Income, and the increase in the liability under the plan is accounted for as Other Expense in the statements of income.

Supplemental Executive Retirement Plan

OGE Energy provides a supplemental executive retirement plan in order to attract and retain lateral hires or other executives designated by the Compensation Committee of OGE Energy's Board of Directors who may not otherwise qualify for a sufficient level of benefits under OGE Energy's Pension Plan and Restoration of Retirement Income Plan. The supplemental executive retirement plan is intended to be an unfunded plan and not subject to the benefit limitations of the Code. For the actuarial equivalence calculations, the supplemental executive retirement plan provides that (i) mortality rates shall be based on the unisex mortality table issued under Internal Revenue Service Notice 2018-02 for purposes of determining the minimum present value under Code Section 417(e)(3) for distributions with annuity starting dates that occur during stability periods beginning in the 2019 calendar year and (ii) the interest rate shall be five percent.