v3.25.4

Retirement Benefits

12 Months Ended

Dec. 31, 2025

Defined Benefit Plan Disclosure [Line Items]

Retirement Benefits

Retirement Benefits

Benefit Plans: CMS Energy and Consumers provide pension, OPEB, and other retirement benefits to eligible employees under a number of different plans. These plans include:

•non‑contributory, qualified DB Pension Plans (closed to new non‑union participants as of July 1, 2003 and closed to new union participants as of September 1, 2005)

•a non‑contributory, qualified DCCP for employees hired on or after July 1, 2003

•benefits to certain management employees under a non‑contributory, nonqualified DB SERP (closed to new participants as of March 31, 2006)

•a non‑contributory, nonqualified DC SERP for certain management employees hired or promoted on or after April 1, 2006

•a contributory, qualified defined contribution 401(k) plan

•health care and life insurance benefits under an OPEB Plan

DB Pension Plans: Participants in the pension plans include present and former employees of CMS Energy and Consumers, including certain present and former affiliates and subsidiaries. Pension plan trust assets are not distinguishable by company. Effective December 31, 2017, CMS Energy’s and Consumers’ then-existing pension plan was amended to include only retired and former employees already covered; this amended plan is referred to as DB Pension Plan B. Also effective December 31, 2017, active employees were moved to a newly created pension plan, referred to as DB Pension Plan A, whose benefits mirror those provided under DB Pension Plan B. Maintaining separate plans for the two groups allows CMS Energy and Consumers to employ a more targeted investment strategy and provides additional opportunities to mitigate risk and volatility.

DCCP: CMS Energy and Consumers provide an employer contribution to the DCCP 401(k) plan for employees hired on or after July 1, 2003. The contribution ranges from 5 percent to 10 percent of base pay, depending on years of service and employee class. Employees are not required to contribute in order to receive the plan’s employer contribution. DCCP expense for CMS Energy, including Consumers, was $57 million for the year ended December 31, 2025, $53 million for the year ended December 31, 2024, and $51 million for the year ended December 31, 2023. DCCP expense for Consumers was $55 million for the year ended December 31, 2025, $52 million for the year ended December 31, 2024, and $50 million for the year ended December 31, 2023.

DB SERP: The DB SERP is a nonqualified plan as defined by the Internal Revenue Code. DB SERP benefits are paid from a rabbi trust. The trust assets are not considered plan assets under ASC 715. DB SERP rabbi trust earnings are taxable. Presented in the following table are the fair values of trust assets and ABO for CMS Energy’s and Consumers’ DB SERP:

In Millions
Years Ended December 31			2025						2024
CMS Energy, including Consumers
Trust assets						$	122					$	127
ABO						104						105
Consumers
Trust assets						$	92					$	95
ABO						76						76

Neither CMS Energy nor Consumers made any contributions to the DB SERP in 2025 or 2024.

DC SERP: On April 1, 2006, CMS Energy and Consumers implemented a DC SERP and froze further new participation in the DB SERP. The DC SERP provides participants benefits ranging from 5 percent to 15 percent of total compensation. The DC SERP requires a minimum of five years of participation before vesting. CMS Energy’s and Consumers’ contributions to the plan, if any, are placed in a grantor trust. For CMS Energy and Consumers, trust assets were $18 million at December 31, 2025 and $17 million at December 31, 2024. DC SERP assets are included in other non‑current assets on CMS Energy’s and Consumers’ consolidated balance sheets. CMS Energy’s and Consumers’ DC SERP expense was $1 million for the years ended December 31, 2025, 2024, and 2023.

401(k) Plan: The 401(k) plan employer match equals 4 to 6 percent of employee eligible contributions based on an employee’s wages and class. The total 401(k) plan cost for CMS Energy, including Consumers, was $46 million for the year ended December 31, 2025, and $41 million for the years ended December 31, 2024 and 2023. The total 401(k) plan cost for Consumers was $44 million for the year ended December 31, 2025, $39 million for the year ended December 31, 2024, and $40 million for the year ended December 31, 2023.

Health-related OPEB Plan: Participants in the health-related OPEB Plan include regular full-time employees covered by the employee health care plan on the day before retirement from either CMS Energy or Consumers at age 55 or older with at least ten full years of applicable continuous service and hired before January 1, 2007 for non-union participants and hired before September 1, 2010 for union participants. Regular full-time employees who qualify for disability retirement under the DB Pension Plans or are disabled and covered by the DCCP and who have 15 years of applicable continuous service may also participate in the health-related OPEB Plan if hired before January 1, 2007 for non-union participants and hired before September 1, 2010 for union participants. Retiree health care costs were based on the assumption that costs would increase 8.00 percent in 2026 and 8.50 percent in 2025 for those under 65 and would increase 9.75 percent in 2026 and 10.25 percent in 2025 for those over 65. The rate of increase was assumed to decline to 4.75 percent by 2034 and thereafter for all retirees.

Assumptions: Presented in the following table are the weighted-average assumptions used in CMS Energy’s, including Consumers’, retirement benefit plans to determine benefit obligations and net periodic benefit cost:

December 31			2025			2024			2023
Weighted average for benefit obligations1
Discount rate2
DB Pension Plan A			5.58		%	5.73		%	5.05		%
DB Pension Plan B			5.28			5.59			4.95
DB SERP			5.22			5.56			4.94
OPEB Plan			5.50			5.69			5.02
Rate of compensation increase
DB Pension Plan A			3.70			3.70			3.60
Weighted average for net periodic benefit cost1
Service cost discount rate2,3
DB Pension Plan A			5.77		%	5.08		%	5.27		%
DB SERP4			—			—			5.18
OPEB Plan			5.85			5.12			5.31
Interest cost discount rate2,3
DB Pension Plan A			5.43			4.93			5.12
DB Pension Plan B			5.30			4.87			5.06
DB SERP			5.29			4.87			5.06
OPEB Plan			5.39			4.91			5.10
Expected long-term rate of return on plan assets5
DB Pension Plans			7.30			7.50			7.20
OPEB Plan			7.15			7.50			7.20
Rate of compensation increase
DB Pension Plan A			3.70			3.60			3.60
DB SERP4			—			—			5.50

1The mortality assumption for benefit obligations and net periodic benefit cost was based on the Pri-2012 Mortality Table, with improvement scale MP-2021.

2The discount rate reflects the rate at which benefits could be effectively settled and is equal to the equivalent single rate resulting from a yield-curve analysis. This analysis incorporated the projected benefit payments specific to CMS Energy’s and Consumers’ DB Pension Plans and OPEB Plan and the yields on high-quality corporate bonds rated Aa or better.

3CMS Energy and Consumers have elected to use a full-yield-curve approach in the estimation of service cost and interest cost; this approach applies individual spot rates along the yield curve to future projected benefit payments based on the time of payment.

4The last active participant in the DB SERP retired in 2023. Thus, the determination of the associated net periodic benefit cost no longer assumes a service cost discount rate nor a rate of compensation increase.

5CMS Energy and Consumers determined the long-term rate of return using historical market returns, the present and expected future economic environment, the capital market principles of risk and return, and the expert opinions of individuals and firms with financial market knowledge. CMS Energy and Consumers considered the asset allocation of the portfolio in forecasting the future expected total return of the portfolio. The goal was to determine a long-term rate of return that could be incorporated into the planning

of future cash flow requirements in conjunction with the change in the liability. Annually, CMS Energy and Consumers review for reasonableness and appropriateness the forecasted returns for various classes of assets used to construct an expected return model. CMS Energy’s and Consumers’ expected long-term rate of return on the assets of the DB Pension Plans was 7.30 percent in 2025. The actual return on the assets of the DB Pension Plans was 12.7 percent in 2025, 3.6 percent in 2024, and 12.6 percent in 2023.

Costs: Presented in the following table are the costs (credits) and other changes in plan assets and benefit obligations incurred in CMS Energy’s and Consumers’ retirement benefit plans:

In Millions
																		DB Pension Plans and DB SERP																																				OPEB Plan
Years Ended December 31												2025						2024						2023																		2025						2024						2023
CMS Energy, including Consumers
Net periodic credit
Service cost																					$	25					$	28					$	29																							$	8					$	11					$	12
Interest cost																					114						109						112																								43						43						44
Expected return on plan assets																					(229)						(234)						(220)																								(111)						(115)						(103)
Amortization of:
Net loss																					11						12						12																								3						4						12
Prior service cost (credit)																					4						4						4																								(34)						(31)						(41)
Settlement loss																					11						11						11																								—						—						—
Net periodic credit																					$	(64)					$	(70)					$	(52)																							$	(91)					$	(88)					$	(76)
Consumers
Net periodic credit
Service cost																					$	24					$	27					$	28																							$	8					$	11					$	11
Interest cost																					106						102						105																								42						41						42
Expected return on plan assets																					(215)						(221)						(208)																								(104)						(107)						(95)
Amortization of:
Net loss																					10						11						11																								3						4						12
Prior service cost (credit)																					4						4						4																								(33)						(30)						(40)
Settlement loss																					11						11						11																								—						—						—
Net periodic credit																					$	(60)					$	(66)					$	(49)																							$	(84)					$	(81)					$	(70)

In Consumers’ electric and gas rate cases, the MPSC approved a mechanism allowing Consumers to defer for future recovery or refund pension and OPEB expenses above or below the amounts used to set existing rates. Amounts deferred will be collected from or refunded to customers over ten years. At December 31, 2025, CMS Energy, including Consumers, had deferred $3 million of pension costs and $6 million of OPEB credits under this mechanism related to 2025 expense. At December 31, 2024, CMS Energy, including Consumers, had deferred $15 million of pension credits and $11 million of OPEB credits under this mechanism related to 2024 expense. At December 31, 2023, CMS Energy, including Consumers, had deferred $11 million of pension credits and $23 million of OPEB costs under this mechanism related to 2023 expense.

CMS Energy and Consumers amortize net gains and losses in excess of 10 percent of the greater of the PBO or the MRV over the average remaining service period for DB Pension Plan A and the OPEB Plan and over the average remaining life expectancy of participants for DB Pension Plan B. For DB Pension Plan A, the estimated period of amortization of gains and losses was seven years for the year ended December 31, 2025, and eight years for the years ended December 31, 2024 and 2023. For DB Pension Plan B, the estimated period of amortization of gains and losses was 17 years for the years ended

December 31, 2025, 2024, and 2023. For the OPEB Plan, the estimated amortization period was nine years for the years ended December 31, 2025, 2024, and 2023.

Prior service cost (credit) amortization is established in the year in which the prior service cost (credit) first occurred, and is based on the same amortization period for all future years until the prior service cost (credit) is fully amortized. CMS Energy and Consumers had new prior service costs for OPEB in 2024. The estimated period of amortization of these new prior service costs is seven years.

CMS Energy and Consumers determine the MRV for the assets of the DB Pension Plans as the fair value of plan assets on the measurement date, adjusted by the gains or losses that will not be admitted into the MRV until future years. CMS Energy and Consumers reflect each year’s gain or loss in the MRV in equal amounts over a five‑year period beginning on the date the original amount was determined. CMS Energy and Consumers determine the MRV for OPEB Plan assets as the fair value of assets on the measurement date.

Reconciliations: Presented in the following table are reconciliations of the funded status of CMS Energy’s and Consumers’ retirement benefit plans with their retirement benefit plans’ liabilities:

In Millions
			DB Pension Plans															DB SERP															OPEB Plan
Years Ended December 31			2025						2024									2025						2024									2025						2024
CMS Energy, including Consumers
Benefit obligation at beginning of period						$	2,094					$	2,195								$	105					$	114								$	831					$	900
Service cost						25						28									—						—									8						11
Interest cost						109						104									5						5									43						43
Plan amendments						—						—									—						—									—						(25)
Actuarial loss (gain)						53			1			(91)			1						4						(4)									2			1			(40)			1
Benefits paid						(158)						(142)									(10)						(10)									(54)						(58)
Benefit obligation at end of period						$	2,123					$	2,094								$	104					$	105								$	830					$	831
Plan assets at fair value at beginning of period						$	2,964					$	3,004								$	—					$	—								$	1,588					$	1,559
Actual return on plan assets						371						102									—						—									197						86
Company contribution						—						—									10						10									—						—
Actual benefits paid						(158)						(142)									(10)						(10)									(52)						(57)
Plan assets at fair value at end of period						$	3,177					$	2,964								$	—					$	—								$	1,733					$	1,588
Funded status						$	1,054		2			$	870		2						$	(104)					$	(105)								$	903					$	757
Consumers
Benefit obligation at beginning of period																					$	76					$	83								$	801					$	867
Service cost																					—						—									8						11
Interest cost																					4						4									42						41
Plan amendments																					—						—									—						(24)
Actuarial loss (gain)																					3						(4)									1			1			(38)			1
Benefits paid																					(7)						(7)									(51)						(56)
Benefit obligation at end of period																					$	76					$	76								$	801					$	801
Plan assets at fair value at beginning of period																					$	—					$	—								$	1,479					$	1,453
Actual return on plan assets																					—						—									184						80
Company contribution																					7						7									—						—
Actual benefits paid																					(7)						(7)									(50)						(54)
Plan assets at fair value at end of period																					$	—					$	—								$	1,613					$	1,479
Funded status																					$	(76)					$	(76)								$	812					$	678

1The actuarial losses for 2025 for the DB Pension Plans and OPEB Plans were primarily the result of lower discount rates. The actuarial gains for 2024 for the DB Pension Plans and OPEB Plan were primarily the result of higher discount rates.

2The total funded status of the DB Pension Plans attributable to Consumers, based on an allocation of expenses, was $1.0 billion at December 31, 2025 and $836 million at December 31, 2024.

Presented in the following table is the classification of CMS Energy’s and Consumers’ retirement benefit plans’ assets and liabilities:

In Millions
December 31			2025						2024
CMS Energy, including Consumers
Non-current assets
DB Pension Plans						$	1,054					$	870
OPEB Plan						903						757
Current liabilities
DB SERP						10						10
Non-current liabilities
DB SERP						94						95
Consumers
Non-current assets
DB Pension Plans						$	1,009					$	836
OPEB Plan						812						678
Current liabilities
DB SERP						7						7
Non-current liabilities
DB SERP						69						69

The ABO for the DB Pension Plans was $1.9 billion at December 31, 2025 and $1.9 billion at December 31, 2024. At December 31, 2025 and 2024, the PBO and ABO did not exceed plan assets for any of the defined benefit pension plans.

Items Not Yet Recognized as a Component of Net Periodic Benefit Cost: Presented in the following table are the amounts recognized in regulatory assets and AOCI that have not been recognized as components of net periodic benefit cost. For additional details on regulatory assets see Note 3, Regulatory Matters.

In Millions
			DB Pension Plans and DB SERP															OPEB Plan
December 31			2025						2024									2025						2024
CMS Energy, including Consumers
Regulatory assets
Net loss						$	548					$	653								$	93					$	176
Prior service cost (credit)						9						12									(61)						(94)
Regulatory assets						$	557					$	665								$	32					$	82
AOCI
Net loss (gain)						57						60									(7)						(3)
Prior service credit						—						—									(2)						(2)
Total amounts recognized in regulatory assets and AOCI						$	614					$	725								$	23					$	77
Consumers
Regulatory assets
Net loss						$	548					$	653								$	93					$	176
Prior service cost (credit)						9						12									(61)						(94)
Regulatory assets						$	557					$	665								$	32					$	82
AOCI
Net loss						18						15									—						—
Total amounts recognized in regulatory assets and AOCI						$	575					$	680								$	32					$	82

Plan Assets: Presented in the following tables are the fair values of the assets of CMS Energy’s, including Consumers’, DB Pension Plans and OPEB Plan, by asset category and by level within the fair value hierarchy. For additional details regarding the fair value hierarchy, see Note 6, Fair Value Measurements.

In Millions
			DB Pension Plans
			December 31, 2025																					December 31, 2024
			Total						Level 1						Level 2									Total						Level 1						Level 2
Cash and short-term investments						$	162					$	162					$	—								$	148					$	148					$	—
Mutual funds						—						—						—									—						—						—
						$	162					$	162					$	—								$	148					$	148					$	—
Pooled funds						3,015																					2,816
Total						$	3,177																				$	2,964

In Millions
			OPEB Plan
			December 31, 2025																					December 31, 2024
			Total						Level 1						Level 2									Total						Level 1						Level 2
Cash and short-term investments						$	72					$	72					$	—								$	35					$	35					$	—
U.S. government and agencies securities						15						—						15									13						—						13
Corporate debt						69						—						69									68						—						68
State and municipal bonds						4						—						4									2						—						2
Foreign bonds						16						—						16									15						—						15
Common stocks						215						215						—									170						170						—
Mutual funds						75						75						—									53						53						—
						$	466					$	362					$	104								$	356					$	258					$	98
Pooled funds						1,267																					1,232
Total						$	1,733																				$	1,588

Cash and Short-term Investments: Cash and short-term investments consist of money market funds with daily liquidity.

U.S. Government and Agencies Securities: U.S. government and agencies securities consist of U.S. Treasury notes and other debt securities backed by the U.S. government and related agencies. These securities are valued based on quoted market prices.

Corporate Debt: Corporate debt investments consist of investment grade bonds of U.S. issuers from diverse industries. These securities are valued based on quoted market prices, when available, or yields available on comparable securities of issuers with similar credit ratings.

State and Municipal Bonds: State and municipal bonds are valued using a matrix-pricing model that incorporates Level 2 market-based information. The fair value of the bonds is derived from various observable inputs, including benchmark yields, reported securities trades, broker/dealer quotes, bond ratings, and general information on market movements for investment grade state and municipal securities normally considered by market participants when pricing such debt securities.

Foreign Bonds: Foreign corporate and government debt securities are valued based on quoted market prices, when available, or on yields available on comparable securities of issuers with similar credit ratings.

Common Stocks: Common stocks in the OPEB Plan consist of equity securities that are actively managed and tracked to the S&P 500 Index and MSCI All Country World ex‑US. These securities are valued at their quoted closing prices.

Mutual Funds: Mutual funds represent shares in registered investment companies that are priced based on the daily quoted net asset values that are publicly available and are the basis for transactions to buy or sell shares in the funds.

Pooled Funds: Pooled funds include both common and collective trust funds as well as special funds that contain only employee benefit plan assets from two or more unrelated benefit plans. These funds primarily consist of U.S. and foreign equity securities, but also include U.S. and foreign fixed-income securities and multi-asset investments. Since these investments are valued at their net asset value as a practical expedient, they are not classified in the fair value hierarchy.

Asset Allocations: Presented in the following table are the investment components of the assets of CMS Energy’s DB Pension Plans and OPEB Plan as of December 31, 2025:

			DB Pension Plans						OPEB Plan
Fixed-income securities						39.2		%				37.6		%
Equity securities						38.7						42.4
Real asset investments						9.3						8.8
Return-seeking fixed income						7.1						5.6
Liquid alternative investments						4.3						3.7
Cash and cash equivalents						1.4						1.9
						100.0		%				100.0		%

CMS Energy’s target 2025 asset allocation for the assets of the DB Pension Plans was 40‑percent fixed income, 38‑percent equity, 11‑percent real assets, 7‑percent return-seeking fixed income, and 4‑percent liquid alternatives.

CMS Energy established union and non‑union VEBA trusts to fund future retiree health and life insurance benefits known as OPEB. These trusts are funded through the ratemaking process for Consumers and through direct contributions from the non‑utility subsidiaries. CMS Energy’s target 2025 asset allocation for OPEB trusts was 40‑percent fixed income, 38‑percent equity, 11‑percent real assets, 7‑percent return-seeking fixed income, and 4‑percent liquid alternatives.

The goal of these target allocations was to maximize the long-term return on plan assets, while maintaining a prudent level of risk. The level of acceptable risk is a function of the liabilities of the plans. Equity investments are diversified mostly across the S&P 500 Index, with lesser allocations to the S&P MidCap and SmallCap Indexes and Foreign Equity Funds. Fixed-income investments are diversified across investment grade instruments of government and corporate issuers, as well as high-yield and global bond funds. Return-seeking fixed-income investments are diversified exposure to high-yield bonds, emerging market debt, and bank loans. Real asset investments are diversified across core real estate and real estate investment trusts. Liquid alternatives are investments in private funds comprised of different and independent hedge funds with various investment strategies. CMS Energy uses annual liability measurements, quarterly portfolio reviews, and periodic asset/liability studies to evaluate the need for adjustments to the portfolio allocations.

Contributions: Contributions comprise required amounts and discretionary contributions. Neither CMS Energy nor Consumers made any contributions in 2025 or 2024, or plans to contribute to the DB Pension Plans or OPEB Plan in 2026. Actual future contributions will depend on future investment performance, discount rates, and various factors related to the participants of the DB Pension Plans and OPEB Plan. CMS Energy and Consumers will, at a minimum, contribute to the plans as needed to comply with federal funding requirements.

Benefit Payments: Presented in the following table are the expected benefit payments for each of the next five years and the five‑year period thereafter:

In Millions
			DB Pension Plans						DB SERP						OPEB Plan
CMS Energy, including Consumers
2026						$	164					$	10					$	59
2027						165						10						61
2028						164						10						62
2029						164						9						62
2030						164						9						62
2031-2035						801						41						305
Consumers
2026						$	154					$	7					$	57
2027						155						7						58
2028						154						7						59
2029						155						6						59
2030						154						6						60
2031-2035						756						29						292

Collective Bargaining Agreements: At December 31, 2025, unions represented 44 percent of CMS Energy’s employees and 45 percent of Consumers’ employees. The UWUA represents Consumers’ and NorthStar Clean Energy’s operating, maintenance, construction employees and Consumers’ customer contact center employees. The USW represents Consumers’ Zeeland plant employees. Consumers’ union agreements expire in 2030 and the majority of NorthStar Clean Energy’s represented employees have an agreement that expires in 2029.

Consumers Energy Company

Defined Benefit Plan Disclosure [Line Items]

Retirement Benefits

Retirement Benefits

Benefit Plans: CMS Energy and Consumers provide pension, OPEB, and other retirement benefits to eligible employees under a number of different plans. These plans include:

•non‑contributory, qualified DB Pension Plans (closed to new non‑union participants as of July 1, 2003 and closed to new union participants as of September 1, 2005)

•a non‑contributory, qualified DCCP for employees hired on or after July 1, 2003

•benefits to certain management employees under a non‑contributory, nonqualified DB SERP (closed to new participants as of March 31, 2006)

•a non‑contributory, nonqualified DC SERP for certain management employees hired or promoted on or after April 1, 2006

•a contributory, qualified defined contribution 401(k) plan

•health care and life insurance benefits under an OPEB Plan

DB Pension Plans: Participants in the pension plans include present and former employees of CMS Energy and Consumers, including certain present and former affiliates and subsidiaries. Pension plan trust assets are not distinguishable by company. Effective December 31, 2017, CMS Energy’s and Consumers’ then-existing pension plan was amended to include only retired and former employees already covered; this amended plan is referred to as DB Pension Plan B. Also effective December 31, 2017, active employees were moved to a newly created pension plan, referred to as DB Pension Plan A, whose benefits mirror those provided under DB Pension Plan B. Maintaining separate plans for the two groups allows CMS Energy and Consumers to employ a more targeted investment strategy and provides additional opportunities to mitigate risk and volatility.

DCCP: CMS Energy and Consumers provide an employer contribution to the DCCP 401(k) plan for employees hired on or after July 1, 2003. The contribution ranges from 5 percent to 10 percent of base pay, depending on years of service and employee class. Employees are not required to contribute in order to receive the plan’s employer contribution. DCCP expense for CMS Energy, including Consumers, was $57 million for the year ended December 31, 2025, $53 million for the year ended December 31, 2024, and $51 million for the year ended December 31, 2023. DCCP expense for Consumers was $55 million for the year ended December 31, 2025, $52 million for the year ended December 31, 2024, and $50 million for the year ended December 31, 2023.

DB SERP: The DB SERP is a nonqualified plan as defined by the Internal Revenue Code. DB SERP benefits are paid from a rabbi trust. The trust assets are not considered plan assets under ASC 715. DB SERP rabbi trust earnings are taxable. Presented in the following table are the fair values of trust assets and ABO for CMS Energy’s and Consumers’ DB SERP:

In Millions
Years Ended December 31			2025						2024
CMS Energy, including Consumers
Trust assets						$	122					$	127
ABO						104						105
Consumers
Trust assets						$	92					$	95
ABO						76						76

Neither CMS Energy nor Consumers made any contributions to the DB SERP in 2025 or 2024.

DC SERP: On April 1, 2006, CMS Energy and Consumers implemented a DC SERP and froze further new participation in the DB SERP. The DC SERP provides participants benefits ranging from 5 percent to 15 percent of total compensation. The DC SERP requires a minimum of five years of participation before vesting. CMS Energy’s and Consumers’ contributions to the plan, if any, are placed in a grantor trust. For CMS Energy and Consumers, trust assets were $18 million at December 31, 2025 and $17 million at December 31, 2024. DC SERP assets are included in other non‑current assets on CMS Energy’s and Consumers’ consolidated balance sheets. CMS Energy’s and Consumers’ DC SERP expense was $1 million for the years ended December 31, 2025, 2024, and 2023.

401(k) Plan: The 401(k) plan employer match equals 4 to 6 percent of employee eligible contributions based on an employee’s wages and class. The total 401(k) plan cost for CMS Energy, including Consumers, was $46 million for the year ended December 31, 2025, and $41 million for the years ended December 31, 2024 and 2023. The total 401(k) plan cost for Consumers was $44 million for the year ended December 31, 2025, $39 million for the year ended December 31, 2024, and $40 million for the year ended December 31, 2023.

Health-related OPEB Plan: Participants in the health-related OPEB Plan include regular full-time employees covered by the employee health care plan on the day before retirement from either CMS Energy or Consumers at age 55 or older with at least ten full years of applicable continuous service and hired before January 1, 2007 for non-union participants and hired before September 1, 2010 for union participants. Regular full-time employees who qualify for disability retirement under the DB Pension Plans or are disabled and covered by the DCCP and who have 15 years of applicable continuous service may also participate in the health-related OPEB Plan if hired before January 1, 2007 for non-union participants and hired before September 1, 2010 for union participants. Retiree health care costs were based on the assumption that costs would increase 8.00 percent in 2026 and 8.50 percent in 2025 for those under 65 and would increase 9.75 percent in 2026 and 10.25 percent in 2025 for those over 65. The rate of increase was assumed to decline to 4.75 percent by 2034 and thereafter for all retirees.

Assumptions: Presented in the following table are the weighted-average assumptions used in CMS Energy’s, including Consumers’, retirement benefit plans to determine benefit obligations and net periodic benefit cost:

December 31			2025			2024			2023
Weighted average for benefit obligations1
Discount rate2
DB Pension Plan A			5.58		%	5.73		%	5.05		%
DB Pension Plan B			5.28			5.59			4.95
DB SERP			5.22			5.56			4.94
OPEB Plan			5.50			5.69			5.02
Rate of compensation increase
DB Pension Plan A			3.70			3.70			3.60
Weighted average for net periodic benefit cost1
Service cost discount rate2,3
DB Pension Plan A			5.77		%	5.08		%	5.27		%
DB SERP4			—			—			5.18
OPEB Plan			5.85			5.12			5.31
Interest cost discount rate2,3
DB Pension Plan A			5.43			4.93			5.12
DB Pension Plan B			5.30			4.87			5.06
DB SERP			5.29			4.87			5.06
OPEB Plan			5.39			4.91			5.10
Expected long-term rate of return on plan assets5
DB Pension Plans			7.30			7.50			7.20
OPEB Plan			7.15			7.50			7.20
Rate of compensation increase
DB Pension Plan A			3.70			3.60			3.60
DB SERP4			—			—			5.50

1The mortality assumption for benefit obligations and net periodic benefit cost was based on the Pri-2012 Mortality Table, with improvement scale MP-2021.

2The discount rate reflects the rate at which benefits could be effectively settled and is equal to the equivalent single rate resulting from a yield-curve analysis. This analysis incorporated the projected benefit payments specific to CMS Energy’s and Consumers’ DB Pension Plans and OPEB Plan and the yields on high-quality corporate bonds rated Aa or better.

3CMS Energy and Consumers have elected to use a full-yield-curve approach in the estimation of service cost and interest cost; this approach applies individual spot rates along the yield curve to future projected benefit payments based on the time of payment.

4The last active participant in the DB SERP retired in 2023. Thus, the determination of the associated net periodic benefit cost no longer assumes a service cost discount rate nor a rate of compensation increase.

5CMS Energy and Consumers determined the long-term rate of return using historical market returns, the present and expected future economic environment, the capital market principles of risk and return, and the expert opinions of individuals and firms with financial market knowledge. CMS Energy and Consumers considered the asset allocation of the portfolio in forecasting the future expected total return of the portfolio. The goal was to determine a long-term rate of return that could be incorporated into the planning

of future cash flow requirements in conjunction with the change in the liability. Annually, CMS Energy and Consumers review for reasonableness and appropriateness the forecasted returns for various classes of assets used to construct an expected return model. CMS Energy’s and Consumers’ expected long-term rate of return on the assets of the DB Pension Plans was 7.30 percent in 2025. The actual return on the assets of the DB Pension Plans was 12.7 percent in 2025, 3.6 percent in 2024, and 12.6 percent in 2023.

Costs: Presented in the following table are the costs (credits) and other changes in plan assets and benefit obligations incurred in CMS Energy’s and Consumers’ retirement benefit plans:

In Millions
																		DB Pension Plans and DB SERP																																				OPEB Plan
Years Ended December 31												2025						2024						2023																		2025						2024						2023
CMS Energy, including Consumers
Net periodic credit
Service cost																					$	25					$	28					$	29																							$	8					$	11					$	12
Interest cost																					114						109						112																								43						43						44
Expected return on plan assets																					(229)						(234)						(220)																								(111)						(115)						(103)
Amortization of:
Net loss																					11						12						12																								3						4						12
Prior service cost (credit)																					4						4						4																								(34)						(31)						(41)
Settlement loss																					11						11						11																								—						—						—
Net periodic credit																					$	(64)					$	(70)					$	(52)																							$	(91)					$	(88)					$	(76)
Consumers
Net periodic credit
Service cost																					$	24					$	27					$	28																							$	8					$	11					$	11
Interest cost																					106						102						105																								42						41						42
Expected return on plan assets																					(215)						(221)						(208)																								(104)						(107)						(95)
Amortization of:
Net loss																					10						11						11																								3						4						12
Prior service cost (credit)																					4						4						4																								(33)						(30)						(40)
Settlement loss																					11						11						11																								—						—						—
Net periodic credit																					$	(60)					$	(66)					$	(49)																							$	(84)					$	(81)					$	(70)

In Consumers’ electric and gas rate cases, the MPSC approved a mechanism allowing Consumers to defer for future recovery or refund pension and OPEB expenses above or below the amounts used to set existing rates. Amounts deferred will be collected from or refunded to customers over ten years. At December 31, 2025, CMS Energy, including Consumers, had deferred $3 million of pension costs and $6 million of OPEB credits under this mechanism related to 2025 expense. At December 31, 2024, CMS Energy, including Consumers, had deferred $15 million of pension credits and $11 million of OPEB credits under this mechanism related to 2024 expense. At December 31, 2023, CMS Energy, including Consumers, had deferred $11 million of pension credits and $23 million of OPEB costs under this mechanism related to 2023 expense.

CMS Energy and Consumers amortize net gains and losses in excess of 10 percent of the greater of the PBO or the MRV over the average remaining service period for DB Pension Plan A and the OPEB Plan and over the average remaining life expectancy of participants for DB Pension Plan B. For DB Pension Plan A, the estimated period of amortization of gains and losses was seven years for the year ended December 31, 2025, and eight years for the years ended December 31, 2024 and 2023. For DB Pension Plan B, the estimated period of amortization of gains and losses was 17 years for the years ended

December 31, 2025, 2024, and 2023. For the OPEB Plan, the estimated amortization period was nine years for the years ended December 31, 2025, 2024, and 2023.

Prior service cost (credit) amortization is established in the year in which the prior service cost (credit) first occurred, and is based on the same amortization period for all future years until the prior service cost (credit) is fully amortized. CMS Energy and Consumers had new prior service costs for OPEB in 2024. The estimated period of amortization of these new prior service costs is seven years.

CMS Energy and Consumers determine the MRV for the assets of the DB Pension Plans as the fair value of plan assets on the measurement date, adjusted by the gains or losses that will not be admitted into the MRV until future years. CMS Energy and Consumers reflect each year’s gain or loss in the MRV in equal amounts over a five‑year period beginning on the date the original amount was determined. CMS Energy and Consumers determine the MRV for OPEB Plan assets as the fair value of assets on the measurement date.

Reconciliations: Presented in the following table are reconciliations of the funded status of CMS Energy’s and Consumers’ retirement benefit plans with their retirement benefit plans’ liabilities:

In Millions
			DB Pension Plans															DB SERP															OPEB Plan
Years Ended December 31			2025						2024									2025						2024									2025						2024
CMS Energy, including Consumers
Benefit obligation at beginning of period						$	2,094					$	2,195								$	105					$	114								$	831					$	900
Service cost						25						28									—						—									8						11
Interest cost						109						104									5						5									43						43
Plan amendments						—						—									—						—									—						(25)
Actuarial loss (gain)						53			1			(91)			1						4						(4)									2			1			(40)			1
Benefits paid						(158)						(142)									(10)						(10)									(54)						(58)
Benefit obligation at end of period						$	2,123					$	2,094								$	104					$	105								$	830					$	831
Plan assets at fair value at beginning of period						$	2,964					$	3,004								$	—					$	—								$	1,588					$	1,559
Actual return on plan assets						371						102									—						—									197						86
Company contribution						—						—									10						10									—						—
Actual benefits paid						(158)						(142)									(10)						(10)									(52)						(57)
Plan assets at fair value at end of period						$	3,177					$	2,964								$	—					$	—								$	1,733					$	1,588
Funded status						$	1,054		2			$	870		2						$	(104)					$	(105)								$	903					$	757
Consumers
Benefit obligation at beginning of period																					$	76					$	83								$	801					$	867
Service cost																					—						—									8						11
Interest cost																					4						4									42						41
Plan amendments																					—						—									—						(24)
Actuarial loss (gain)																					3						(4)									1			1			(38)			1
Benefits paid																					(7)						(7)									(51)						(56)
Benefit obligation at end of period																					$	76					$	76								$	801					$	801
Plan assets at fair value at beginning of period																					$	—					$	—								$	1,479					$	1,453
Actual return on plan assets																					—						—									184						80
Company contribution																					7						7									—						—
Actual benefits paid																					(7)						(7)									(50)						(54)
Plan assets at fair value at end of period																					$	—					$	—								$	1,613					$	1,479
Funded status																					$	(76)					$	(76)								$	812					$	678

1The actuarial losses for 2025 for the DB Pension Plans and OPEB Plans were primarily the result of lower discount rates. The actuarial gains for 2024 for the DB Pension Plans and OPEB Plan were primarily the result of higher discount rates.

2The total funded status of the DB Pension Plans attributable to Consumers, based on an allocation of expenses, was $1.0 billion at December 31, 2025 and $836 million at December 31, 2024.

Presented in the following table is the classification of CMS Energy’s and Consumers’ retirement benefit plans’ assets and liabilities:

In Millions
December 31			2025						2024
CMS Energy, including Consumers
Non-current assets
DB Pension Plans						$	1,054					$	870
OPEB Plan						903						757
Current liabilities
DB SERP						10						10
Non-current liabilities
DB SERP						94						95
Consumers
Non-current assets
DB Pension Plans						$	1,009					$	836
OPEB Plan						812						678
Current liabilities
DB SERP						7						7
Non-current liabilities
DB SERP						69						69

The ABO for the DB Pension Plans was $1.9 billion at December 31, 2025 and $1.9 billion at December 31, 2024. At December 31, 2025 and 2024, the PBO and ABO did not exceed plan assets for any of the defined benefit pension plans.

Items Not Yet Recognized as a Component of Net Periodic Benefit Cost: Presented in the following table are the amounts recognized in regulatory assets and AOCI that have not been recognized as components of net periodic benefit cost. For additional details on regulatory assets see Note 3, Regulatory Matters.

In Millions
			DB Pension Plans and DB SERP															OPEB Plan
December 31			2025						2024									2025						2024
CMS Energy, including Consumers
Regulatory assets
Net loss						$	548					$	653								$	93					$	176
Prior service cost (credit)						9						12									(61)						(94)
Regulatory assets						$	557					$	665								$	32					$	82
AOCI
Net loss (gain)						57						60									(7)						(3)
Prior service credit						—						—									(2)						(2)
Total amounts recognized in regulatory assets and AOCI						$	614					$	725								$	23					$	77
Consumers
Regulatory assets
Net loss						$	548					$	653								$	93					$	176
Prior service cost (credit)						9						12									(61)						(94)
Regulatory assets						$	557					$	665								$	32					$	82
AOCI
Net loss						18						15									—						—
Total amounts recognized in regulatory assets and AOCI						$	575					$	680								$	32					$	82

Plan Assets: Presented in the following tables are the fair values of the assets of CMS Energy’s, including Consumers’, DB Pension Plans and OPEB Plan, by asset category and by level within the fair value hierarchy. For additional details regarding the fair value hierarchy, see Note 6, Fair Value Measurements.

In Millions
			DB Pension Plans
			December 31, 2025																					December 31, 2024
			Total						Level 1						Level 2									Total						Level 1						Level 2
Cash and short-term investments						$	162					$	162					$	—								$	148					$	148					$	—
Mutual funds						—						—						—									—						—						—
						$	162					$	162					$	—								$	148					$	148					$	—
Pooled funds						3,015																					2,816
Total						$	3,177																				$	2,964

In Millions
			OPEB Plan
			December 31, 2025																					December 31, 2024
			Total						Level 1						Level 2									Total						Level 1						Level 2
Cash and short-term investments						$	72					$	72					$	—								$	35					$	35					$	—
U.S. government and agencies securities						15						—						15									13						—						13
Corporate debt						69						—						69									68						—						68
State and municipal bonds						4						—						4									2						—						2
Foreign bonds						16						—						16									15						—						15
Common stocks						215						215						—									170						170						—
Mutual funds						75						75						—									53						53						—
						$	466					$	362					$	104								$	356					$	258					$	98
Pooled funds						1,267																					1,232
Total						$	1,733																				$	1,588

Cash and Short-term Investments: Cash and short-term investments consist of money market funds with daily liquidity.

U.S. Government and Agencies Securities: U.S. government and agencies securities consist of U.S. Treasury notes and other debt securities backed by the U.S. government and related agencies. These securities are valued based on quoted market prices.

Corporate Debt: Corporate debt investments consist of investment grade bonds of U.S. issuers from diverse industries. These securities are valued based on quoted market prices, when available, or yields available on comparable securities of issuers with similar credit ratings.

State and Municipal Bonds: State and municipal bonds are valued using a matrix-pricing model that incorporates Level 2 market-based information. The fair value of the bonds is derived from various observable inputs, including benchmark yields, reported securities trades, broker/dealer quotes, bond ratings, and general information on market movements for investment grade state and municipal securities normally considered by market participants when pricing such debt securities.

Foreign Bonds: Foreign corporate and government debt securities are valued based on quoted market prices, when available, or on yields available on comparable securities of issuers with similar credit ratings.

Common Stocks: Common stocks in the OPEB Plan consist of equity securities that are actively managed and tracked to the S&P 500 Index and MSCI All Country World ex‑US. These securities are valued at their quoted closing prices.

Mutual Funds: Mutual funds represent shares in registered investment companies that are priced based on the daily quoted net asset values that are publicly available and are the basis for transactions to buy or sell shares in the funds.

Pooled Funds: Pooled funds include both common and collective trust funds as well as special funds that contain only employee benefit plan assets from two or more unrelated benefit plans. These funds primarily consist of U.S. and foreign equity securities, but also include U.S. and foreign fixed-income securities and multi-asset investments. Since these investments are valued at their net asset value as a practical expedient, they are not classified in the fair value hierarchy.

Asset Allocations: Presented in the following table are the investment components of the assets of CMS Energy’s DB Pension Plans and OPEB Plan as of December 31, 2025:

			DB Pension Plans						OPEB Plan
Fixed-income securities						39.2		%				37.6		%
Equity securities						38.7						42.4
Real asset investments						9.3						8.8
Return-seeking fixed income						7.1						5.6
Liquid alternative investments						4.3						3.7
Cash and cash equivalents						1.4						1.9
						100.0		%				100.0		%

CMS Energy’s target 2025 asset allocation for the assets of the DB Pension Plans was 40‑percent fixed income, 38‑percent equity, 11‑percent real assets, 7‑percent return-seeking fixed income, and 4‑percent liquid alternatives.

CMS Energy established union and non‑union VEBA trusts to fund future retiree health and life insurance benefits known as OPEB. These trusts are funded through the ratemaking process for Consumers and through direct contributions from the non‑utility subsidiaries. CMS Energy’s target 2025 asset allocation for OPEB trusts was 40‑percent fixed income, 38‑percent equity, 11‑percent real assets, 7‑percent return-seeking fixed income, and 4‑percent liquid alternatives.

The goal of these target allocations was to maximize the long-term return on plan assets, while maintaining a prudent level of risk. The level of acceptable risk is a function of the liabilities of the plans. Equity investments are diversified mostly across the S&P 500 Index, with lesser allocations to the S&P MidCap and SmallCap Indexes and Foreign Equity Funds. Fixed-income investments are diversified across investment grade instruments of government and corporate issuers, as well as high-yield and global bond funds. Return-seeking fixed-income investments are diversified exposure to high-yield bonds, emerging market debt, and bank loans. Real asset investments are diversified across core real estate and real estate investment trusts. Liquid alternatives are investments in private funds comprised of different and independent hedge funds with various investment strategies. CMS Energy uses annual liability measurements, quarterly portfolio reviews, and periodic asset/liability studies to evaluate the need for adjustments to the portfolio allocations.

Contributions: Contributions comprise required amounts and discretionary contributions. Neither CMS Energy nor Consumers made any contributions in 2025 or 2024, or plans to contribute to the DB Pension Plans or OPEB Plan in 2026. Actual future contributions will depend on future investment performance, discount rates, and various factors related to the participants of the DB Pension Plans and OPEB Plan. CMS Energy and Consumers will, at a minimum, contribute to the plans as needed to comply with federal funding requirements.

Benefit Payments: Presented in the following table are the expected benefit payments for each of the next five years and the five‑year period thereafter:

In Millions
			DB Pension Plans						DB SERP						OPEB Plan
CMS Energy, including Consumers
2026						$	164					$	10					$	59
2027						165						10						61
2028						164						10						62
2029						164						9						62
2030						164						9						62
2031-2035						801						41						305
Consumers
2026						$	154					$	7					$	57
2027						155						7						58
2028						154						7						59
2029						155						6						59
2030						154						6						60
2031-2035						756						29						292

Collective Bargaining Agreements: At December 31, 2025, unions represented 44 percent of CMS Energy’s employees and 45 percent of Consumers’ employees. The UWUA represents Consumers’ and NorthStar Clean Energy’s operating, maintenance, construction employees and Consumers’ customer contact center employees. The USW represents Consumers’ Zeeland plant employees. Consumers’ union agreements expire in 2030 and the majority of NorthStar Clean Energy’s represented employees have an agreement that expires in 2029.

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (k)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
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-Section 50
-Paragraph 5
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 5
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (l)
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-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (j)(1)
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (j)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (j)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-5

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (j)(3)
-Publisher FASB
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