Cover page - shares	3 Months Ended
Cover page - shares	Mar. 31, 2021	Apr. 12, 2021
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	1-9513
Entity Registrant Name	CMS ENERGY CORPORATION
Entity Tax Identification Number	38-2726431
Entity Incorporation, State or Country Code	MI
Entity Address, Address Line One	One Energy Plaza
Entity Address, City or Town	Jackson
Entity Address, State or Province	MI
Entity Address, Postal Zip Code	49201
City Area Code	517
Local Phone Number	788‑0550
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		289,459,560
Entity Central Index Key	0000811156
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Consumers Energy Company
Document Information [Line Items]
Entity File Number	1-5611
Entity Registrant Name	CONSUMERS ENERGY COMPANY
Entity Tax Identification Number	38-0442310
Entity Incorporation, State or Country Code	MI
Entity Address, Address Line One	One Energy Plaza
Entity Address, City or Town	Jackson
Entity Address, State or Province	MI
Entity Address, Postal Zip Code	49201
City Area Code	517
Local Phone Number	788‑0550
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		84,108,789
Entity Central Index Key	0000201533
CMS Energy Corporation Common Stock, $0.01 par value
Document Information [Line Items]
Title of 12(b) Security	CMS Energy Corporation Common Stock, $0.01 par value
Trading Symbol	CMS
Security Exchange Name	NYSE
CMS Energy Corporation 5.625% Junior Subordinated Notes due 2078
Document Information [Line Items]
Title of 12(b) Security	CMS Energy Corporation 5.625% Junior Subordinated Notes due 2078
Trading Symbol	CMSA
Security Exchange Name	NYSE
CMS Energy Corporation 5.875% Junior Subordinated Notes due 2078
Document Information [Line Items]
Title of 12(b) Security	CMS Energy Corporation 5.875% Junior Subordinated Notes due 2078
Trading Symbol	CMSC
Security Exchange Name	NYSE
CMS Energy Corporation 5.875% Junior Subordinated Notes due 2079
Document Information [Line Items]
Title of 12(b) Security	CMS Energy Corporation 5.875% Junior Subordinated Notes due 2079
Trading Symbol	CMSD
Security Exchange Name	NYSE
Consumers Energy Company Cumulative Preferred Stock, $100 par value: $4.50 Series
Document Information [Line Items]
Title of 12(b) Security	Consumers Energy Company Cumulative Preferred Stock, $100 par value: $4.50 Series
Trading Symbol	CMS-PB
Security Exchange Name	NYSE

Consolidated Statements of Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating Revenue	$ 2,083	$ 1,864
Operating Expenses
Fuel for electric generation	138	103
Purchased power – related parties	18	18
Maintenance and other operating expenses	323	315
Depreciation and amortization	340	316
General taxes	123	114
Total operating expenses	1,598	1,496
Operating Income	485	368
Other Income (Expense)
Interest income	1	1
Interest and dividend income – related parties	0	7
Allowance for equity funds used during construction	1	1
Income from equity method investees	2	3
Non-operating retirement benefits, net	41	31
Other income	1	0
Other expense	(2)	(4)
Total other income	44	39
Interest Charges
Interest on long-term debt	119	116
Interest expense – related parties	3	3
Other interest expense	15	19
Allowance for borrowed funds used during construction	(1)	(1)
Total interest charges	136	137
Income Before Income Taxes	393	270
Income Tax Expense	51	27
Net Income	342	243
Loss Attributable to Noncontrolling Interests	(7)	0
Net Income Available to Common Stockholders	$ 349	$ 243
Basic earnings per average common share (in dollars per share)	$ 1.21	$ 0.86
Diluted earnings per average common share (in dollars per share)	$ 1.21	$ 0.85
Consumers Energy Company
Operating Revenue	$ 1,937	$ 1,744
Operating Expenses
Fuel for electric generation	106	79
Purchased and interchange power	367	347
Purchased power – related parties	18	18
Cost of gas sold	278	270
Maintenance and other operating expenses	292	278
Depreciation and amortization	329	312
General taxes	118	111
Total operating expenses	1,508	1,415
Operating Income	429	329
Other Income (Expense)
Interest income	1	1
Interest and dividend income – related parties	1	1
Allowance for equity funds used during construction	1	1
Non-operating retirement benefits, net	38	29
Other income	1	0
Other expense	(2)	(3)
Total other income	40	29
Interest Charges
Interest on long-term debt	73	74
Interest expense – related parties	3	3
Other interest expense	2	3
Allowance for borrowed funds used during construction	(1)	(1)
Total interest charges	77	79
Income Before Income Taxes	392	279
Income Tax Expense	56	44
Net Income	336	235
Net Income Available to Common Stockholders	336	235
Purchased and interchange power
Operating Expenses
Cost of goods and services sold	377	357
Cost of gas sold
Operating Expenses
Cost of goods and services sold	$ 279	$ 273

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net Income	$ 342	$ 243
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax	1	1
Derivatives
Unrealized gain (loss) on derivative instruments, net of tax of $— and $(1)	1	(4)
Other Comprehensive Income (Loss)	2	(3)
Comprehensive Income	344	240
Comprehensive Loss Attributable to Noncontrolling Interests	(7)	0
Comprehensive Income Attributable to CMS Energy	351	240
Consumers Energy Company
Net Income	336	235
Retirement Benefits Liability
Amortization of net actuarial loss, net of tax	0	0
Derivatives
Other Comprehensive Income (Loss)	0	0
Comprehensive Income	$ 336	$ 235

Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Amortization of net actuarial loss, TAX	$ 0	$ 0
Unrealized loss on derivative instruments, TAX	0	(1)
Consumers Energy Company
Amortization of net actuarial loss, TAX	$ 0	$ 1

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash Flows from Operating Activities
Net Income	$ 342	$ 243
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	340	316
Deferred income taxes and investment tax credits	48	67
Other non‑cash operating activities and reconciling adjustments	(17)	9
Pension contributions	0	(531)
Changes in assets and liabilities
Accounts and notes receivable and accrued revenue	30	(17)
Inventories	168	171
Accounts payable and accrued rate refunds	(103)	(54)
Other current and non‑current assets and liabilities	24	(3)
Net cash provided by operating activities	832	201
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under finance lease)	(437)	(523)
Increase in EnerBank notes receivable	(76)	(4)
Purchase of notes receivable by EnerBank	(2)	(8)
Proceeds from sale of EnerBank notes receivable	263	0
Cost to retire property and other investing activities	(31)	(24)
Net cash used in investing activities	(283)	(559)
Cash Flows from Financing Activities
Proceeds from issuance of debt	0	1,198
Retirement of debt	(2)	(2)
Decrease in EnerBank certificates of deposit	(73)	(7)
Decrease in notes payable	0	(90)
Issuance of common stock, net of issuance costs	9	101
Payment of dividends on common stock	(126)	(116)
Other financing costs	(18)	(22)
Net cash provided by (used in) financing activities	(210)	1,062
Net Increase in Cash and Cash Equivalents, Including Restricted Amounts	339	704
Cash and Cash Equivalents, Including Restricted Amounts, Beginning of Period	185	157
Cash and Cash Equivalents, Including Restricted Amounts, End of Period	524	861
Non‑cash transactions
Capital expenditures not paid	87	95
Consumers Energy Company
Cash Flows from Operating Activities
Net Income	336	235
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	329	312
Deferred income taxes and investment tax credits	51	44
Other non‑cash operating activities and reconciling adjustments	(10)	0
Pension contributions	0	(518)
Changes in assets and liabilities
Accounts and notes receivable and accrued revenue	39	31
Inventories	168	170
Accounts payable and accrued rate refunds	(99)	(54)
Other current and non‑current assets and liabilities	27	18
Net cash provided by operating activities	841	238
Cash Flows from Investing Activities
Capital expenditures (excludes assets placed under finance lease)	(433)	(520)
Cost to retire property and other investing activities	(25)	(22)
Net cash used in investing activities	(458)	(542)
Cash Flows from Financing Activities
Proceeds from issuance of debt	0	873
Decrease in notes payable	0	(90)
Decrease in notes payable – related parties	(250)	0
Stockholder contribution	150	350
Payment of dividends on common stock	(276)	(219)
Other financing costs	(8)	(10)
Net cash provided by (used in) financing activities	(384)	904
Net Increase in Cash and Cash Equivalents, Including Restricted Amounts	(1)	600
Cash and Cash Equivalents, Including Restricted Amounts, Beginning of Period	35	28
Cash and Cash Equivalents, Including Restricted Amounts, End of Period	34	628
Non‑cash transactions
Capital expenditures not paid	$ 84	$ 85

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Current Assets
Cash and cash equivalents	$ 496	$ 168
Restricted cash and cash equivalents	28	17
Accounts receivable and accrued revenue	839	863
Notes receivable, less allowance of $29 in 2021 and $32 in 2020	284	275
Accounts receivable – related parties	17	19
Inventories at average cost
Gas in underground storage	195	353
Materials and supplies	162	155
Generating plant fuel stock	50	68
Deferred property taxes	267	332
Regulatory assets	30	42
Prepayments and other current assets	145	112
Total current assets	2,513	2,404
Plant, Property, and Equipment
Plant, property, and equipment, gross	28,457	27,907
Less accumulated depreciation and amortization	8,178	7,953
Plant, property, and equipment, net	20,279	19,954
Construction work in progress	928	1,085
Total plant, property, and equipment	21,207	21,039
Other Non‑current Assets
Regulatory assets	2,613	2,653
Accounts and notes receivable, less allowance of $89 in 2021 and $91 in 2020	2,445	2,631
Investments	72	70
Other	873	869
Total other non‑current assets	6,003	6,223
Total Assets	29,723	29,666
Current Liabilities
Current portion of long-term debt, finance leases, and other financing	1,506	1,506
Accounts payable	538	671
Accounts payable – related parties	7	7
Accrued rate refunds	2	20
Accrued interest	113	106
Accrued taxes	360	457
Regulatory liabilities	204	151
Other current liabilities	155	156
Total current liabilities	2,885	3,074
Non‑current Liabilities
Long-term debt	13,561	13,634
Non-current portion of finance leases and other financing	51	56
Regulatory liabilities	3,772	3,744
Postretirement benefits	151	152
Asset retirement obligations	564	553
Deferred investment tax credit	114	115
Deferred income taxes	1,926	1,863
Other non‑current liabilities	397	398
Total non‑current liabilities	20,536	20,515
Commitments and Contingencies
Common stockholders’ equity
Common stock	3	3
Other paid-in capital	5,371	5,365
Accumulated other comprehensive loss	(84)	(86)
Retained earnings	437	214
Total common stockholders’ equity	5,727	5,496
Noncontrolling interests	575	581
Total equity	6,302	6,077
Total Liabilities and Equity	29,723	29,666
Consumers Energy Company
Current Assets
Cash and cash equivalents	9	20
Restricted cash and cash equivalents	25	15
Accounts receivable and accrued revenue	801	828
Accounts receivable – related parties	9	18
Inventories at average cost
Gas in underground storage	195	353
Materials and supplies	156	149
Generating plant fuel stock	49	67
Deferred property taxes	267	332
Regulatory assets	30	42
Prepayments and other current assets	119	68
Total current assets	1,660	1,892
Plant, Property, and Equipment
Plant, property, and equipment, gross	27,299	26,757
Less accumulated depreciation and amortization	8,058	7,844
Plant, property, and equipment, net	19,241	18,913
Construction work in progress	887	1,058
Total plant, property, and equipment	20,128	19,971
Other Non‑current Assets
Regulatory assets	2,613	2,653
Accounts and notes receivable, less allowance of $89 in 2021 and $91 in 2020	25	25
Accounts and notes receivable – related parties	104	105
Other	750	753
Total other non‑current assets	3,492	3,536
Total Assets	25,280	25,399
Current Liabilities
Current portion of long-term debt, finance leases, and other financing	384	384
Notes payable – related parties	57	307
Accounts payable	501	636
Accounts payable – related parties	12	7
Accrued rate refunds	2	20
Accrued interest	79	72
Accrued taxes	364	458
Regulatory liabilities	204	151
Other current liabilities	106	104
Total current liabilities	1,709	2,139
Non‑current Liabilities
Long-term debt	7,743	7,742
Non-current portion of finance leases and other financing	51	56
Regulatory liabilities	3,772	3,744
Postretirement benefits	111	112
Asset retirement obligations	541	530
Deferred investment tax credit	114	115
Deferred income taxes	2,159	2,094
Other non‑current liabilities	314	311
Total non‑current liabilities	14,805	14,704
Commitments and Contingencies
Common stockholders’ equity
Common stock	841	841
Other paid-in capital	6,174	6,024
Accumulated other comprehensive loss	(36)	(36)
Retained earnings	1,750	1,690
Total common stockholders’ equity	8,729	8,519
Cumulative preferred stock, $4.50 series	37	37
Total equity	8,766	8,556
Total Liabilities and Equity	$ 25,280	$ 25,399

Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Accounts receivable and accrued revenue, ALLOWANCE	$ 27	$ 29
Notes receivable, ALLOWANCE	29	32
Accounts and notes receivable, ALLOWANCE	$ 89	$ 91
Common stock authorized (in shares)	350,000,000.0	350,000,000.0
Common stock outstanding (in shares)	289,500,000	288,900,000
Consumers Energy Company
Accounts receivable and accrued revenue, ALLOWANCE	$ 27	$ 29
Common stock authorized (in shares)	125,000,000.0	125,000,000.0
Common stock outstanding (in shares)	84,100,000	84,100,000

Consolidated Statements of Changes In Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock	Other Paid-in Capital	Accumulated Other Comprehensive Loss	Retirement benefits liability	Derivative instruments	Retained Earnings (Accumulated Deficit)	Retained Earnings (Accumulated Deficit) Cumulative Effect, Period of Adoption, Adjustment	Noncontrolling Interests	Consumers Energy Company	Consumers Energy Company Common Stock	Consumers Energy Company Other Paid-in Capital	Consumers Energy Company Accumulated Other Comprehensive Loss	Consumers Energy Company Retirement benefits liability	Consumers Energy Company Retained Earnings (Accumulated Deficit)	Consumers Energy Company Cumulative Preferred Stock
Total Equity at Beginning of Period at Dec. 31, 2019	$ 5,055	$ 3	$ 5,113	$ (73)	$ (69)	$ (4)	$ (25)	$ (51)	$ 37	$ 7,737	$ 841	$ 5,374	$ (28)	$ (28)	$ 1,513	$ 37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued			106
Common stock repurchased			(12)
Stockholder contribution												350
Amortization of net actuarial loss	1				1					0
Unrealized gain (loss) on derivative instruments	(4)					(4)
Net Income	243						243		0	235					235
Dividends declared on common stock							(116)								(219)
Contribution from noncontrolling interest									0
Total Equity at End of Period at Mar. 31, 2020	$ 5,222	3	5,207	(76)	(68)	(8)	51		37	8,103	841	5,724	(28)	(28)	1,529	37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per common share (in dollars per share)	$ 0.4075
Total Equity at Beginning of Period at Dec. 31, 2020	$ 6,077	3	5,365	(86)	(80)	(6)	214	$ 0	581	8,556	841	6,024	(36)	(36)	1,690	37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued			15
Common stock repurchased			(9)
Stockholder contribution												150
Amortization of net actuarial loss	1				1					0
Unrealized gain (loss) on derivative instruments	1					1
Net Income	342						349		(7)	336					336
Dividends declared on common stock							(126)								(276)
Contribution from noncontrolling interest									1
Total Equity at End of Period at Mar. 31, 2021	$ 6,302	$ 3	$ 5,371	$ (84)	$ (79)	$ (5)	$ 437		$ 575	$ 8,766	$ 841	$ 6,174	$ (36)	$ (36)	$ 1,750	$ 37
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per common share (in dollars per share)	$ 0.4350

Regulatory Matters	3 Months Ended
Regulatory Matters	Mar. 31, 2021
Public Utilities, General Disclosures [Line Items]
Regulatory Matters	Regulatory Matters Regulatory matters are critical to Consumers. The Michigan Attorney General, ABATE, the MPSC Staff, and certain other parties typically participate in MPSC proceedings concerning Consumers, such as Consumers’ rate cases and PSCR and GCR processes. These parties often challenge various aspects of those proceedings, including the prudence of Consumers’ policies and practices, and seek cost disallowances and other relief. The parties also have appealed significant MPSC orders. Depending upon the specific issues, the outcomes of rate cases and proceedings, including judicial proceedings challenging MPSC orders or other actions, could negatively affect CMS Energy’s and Consumers’ liquidity, financial condition, and results of operations. Consumers cannot predict the outcome of these proceedings. There are multiple appeals pending that involve various issues concerning cost recovery from customers, the adequacy of the record of evidence supporting the recovery of Smart Energy investments, and other matters. Consumers is unable to predict the outcome of these appeals. Reserve for Customer Refunds: In December 2020, the MPSC issued an order authorizing Consumers to refund $28 million voluntarily to utility customers. In February 2021, Consumers submitted a filing proposing that the refund take the form of incremental spending in 2021 above amounts included in rates on various programs, including electric service restoration and gas and electric technology expenses. Consumers’ proposal indicates that if it does not achieve the incremental spending, the remaining balance would be provided to electric or gas utility customers through a bill credit. Consumers had recorded a current regulatory liability of $28 million at March 31, 2021 and December 31, 2020 related to this voluntary refund. Voluntary Transmission Asset Sale Gain Share: In October 2020, Consumers completed a sale of the electric utility’s remaining transmission equipment to METC. In December 2020, Consumers filed an application with the MPSC requesting approval to share voluntarily half of the gain from the sale with electric utility customers; this application was approved by the MPSC in February 2021. Consumers will share the gain through incremental service restoration spending in 2021 above amounts included in rates or through a bill credit to electric utility customers in 2022. As a result, the $14 million gain to be shared with customers was recorded on Consumers’ consolidated balance sheets as a current regulatory liability at March 31, 2021 and December 31, 2020. Energy Waste Reduction Plan Incentive: Consumers will file its 2020 energy waste reduction reconciliation in 2021, requesting the MPSC’s approval to collect from customers the maximum performance incentive of $42 million for exceeding statutory savings targets in 2020. Consumers recognized incentive revenue under this program of $42 million in 2020.
Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Regulatory Matters	Regulatory Matters Regulatory matters are critical to Consumers. The Michigan Attorney General, ABATE, the MPSC Staff, and certain other parties typically participate in MPSC proceedings concerning Consumers, such as Consumers’ rate cases and PSCR and GCR processes. These parties often challenge various aspects of those proceedings, including the prudence of Consumers’ policies and practices, and seek cost disallowances and other relief. The parties also have appealed significant MPSC orders. Depending upon the specific issues, the outcomes of rate cases and proceedings, including judicial proceedings challenging MPSC orders or other actions, could negatively affect CMS Energy’s and Consumers’ liquidity, financial condition, and results of operations. Consumers cannot predict the outcome of these proceedings. There are multiple appeals pending that involve various issues concerning cost recovery from customers, the adequacy of the record of evidence supporting the recovery of Smart Energy investments, and other matters. Consumers is unable to predict the outcome of these appeals. Reserve for Customer Refunds: In December 2020, the MPSC issued an order authorizing Consumers to refund $28 million voluntarily to utility customers. In February 2021, Consumers submitted a filing proposing that the refund take the form of incremental spending in 2021 above amounts included in rates on various programs, including electric service restoration and gas and electric technology expenses. Consumers’ proposal indicates that if it does not achieve the incremental spending, the remaining balance would be provided to electric or gas utility customers through a bill credit. Consumers had recorded a current regulatory liability of $28 million at March 31, 2021 and December 31, 2020 related to this voluntary refund. Voluntary Transmission Asset Sale Gain Share: In October 2020, Consumers completed a sale of the electric utility’s remaining transmission equipment to METC. In December 2020, Consumers filed an application with the MPSC requesting approval to share voluntarily half of the gain from the sale with electric utility customers; this application was approved by the MPSC in February 2021. Consumers will share the gain through incremental service restoration spending in 2021 above amounts included in rates or through a bill credit to electric utility customers in 2022. As a result, the $14 million gain to be shared with customers was recorded on Consumers’ consolidated balance sheets as a current regulatory liability at March 31, 2021 and December 31, 2020. Energy Waste Reduction Plan Incentive: Consumers will file its 2020 energy waste reduction reconciliation in 2021, requesting the MPSC’s approval to collect from customers the maximum performance incentive of $42 million for exceeding statutory savings targets in 2020. Consumers recognized incentive revenue under this program of $42 million in 2020.

Contingencies and Commitments

3 Months Ended

Mar. 31, 2021

Other Commitments [Line Items]

Contingencies and Commitments

CMS Energy and Consumers are involved in various matters that give rise to contingent liabilities. Depending on the specific issues, the resolution of these contingencies could negatively affect CMS Energy’s and Consumers’ liquidity, financial condition, and results of operations. In their disclosures of these matters, CMS Energy and Consumers provide an estimate of the possible loss or range of loss when such an estimate can be made. Disclosures that state that CMS Energy or Consumers cannot predict the outcome of a matter indicate that they are unable to estimate a possible loss or range of loss for the matter.

CMS Energy Contingencies

Bay Harbor: CMS Land retained environmental remediation obligations for the collection and treatment of leachate at Bay Harbor after selling its interests in the development in 2002. Leachate is produced when water enters into cement kiln dust piles left over from former cement plant operations at the site. In 2012, CMS Land and EGLE finalized an agreement that established the final remedies and the future water quality criteria at the site. CMS Land completed all construction necessary to implement the remedies required by the agreement and will continue to maintain and operate a system to discharge treated leachate into Little Traverse Bay under an NPDES permit, which was valid through September 2020. CMS Land submitted a renewal request for the permit in April 2020. CMS Land is allowed to continue operating under the previous NPDES permit until a response is received from EGLE.

At March 31, 2021, CMS Energy had a recorded liability of $45 million for its remaining obligations for environmental remediation. CMS Energy calculated this liability based on discounted projected costs, using a discount rate of 4.34 percent and an inflation rate of one percent on annual operating and maintenance costs. The undiscounted amount of the remaining obligation is $56 million. CMS Energy expects to pay the following amounts for long-term leachate disposal and operating and maintenance costs during the remainder of 2021 and in each of the next five years:


In Millions
	2021			2022			2023			2024			2025			2026
CMS Energy
Long-term leachate disposal and operating and maintenance costs		$	3		$	4		$	4		$	4		$	4		$	4

CMS Energy’s estimate of response activity costs and the timing of expenditures could change if there are changes in circumstances or assumptions used in calculating the liability. Although a liability for its present estimate of remaining response activity costs has been recorded, CMS Energy cannot predict the ultimate financial impact or outcome of this matter.

Equatorial Guinea Tax Claim: In 2002, CMS Energy sold its oil, gas, and methanol investments in Equatorial Guinea. The government of Equatorial Guinea claims that, in connection with the sale, CMS Energy owes $152 million in taxes, plus substantial penalties and interest that could be up to or

exceed the amount of the taxes claimed. In 2015, the matter was proceeding to formal arbitration; however, since then, the government of Equatorial Guinea has stopped communicating. CMS Energy has concluded that the government’s tax claim is without merit and believes the likelihood of material loss to be remote, but cannot predict the financial impact or outcome of the matter. An unfavorable outcome could have a material adverse effect on CMS Energy’s liquidity, financial condition, and results of operations.

Consumers Electric Utility Contingencies

Electric Environmental Matters: Consumers’ operations are subject to environmental laws and regulations. Historically, Consumers has generally been able to recover, in customer rates, the costs to operate its facilities in compliance with these laws and regulations.

Cleanup and Solid Waste: Consumers expects to incur remediation and other response activity costs at a number of sites under NREPA. Consumers believes that these costs should be recoverable in rates, but cannot guarantee that outcome. Consumers estimates that its liability for NREPA sites for which it can estimate a range of loss will be between $2 million and $4 million. At March 31, 2021, Consumers had a recorded liability of $2 million, the minimum amount in the range of its estimated probable NREPA liability, as no amount in the range was considered a better estimate than any other amount.

Consumers is a potentially responsible party at a number of contaminated sites administered under CERCLA. CERCLA liability is joint and several. In 2010, Consumers received official notification from the EPA that identified Consumers as a potentially responsible party for cleanup of PCBs at the Kalamazoo River CERCLA site. The notification claimed that the EPA has reason to believe that Consumers disposed of PCBs and arranged for the disposal and treatment of PCB-containing materials at portions of the site. In 2011, Consumers received a follow-up letter from the EPA requesting that Consumers agree to participate in a removal action plan along with several other companies for an area of lower Portage Creek, which is connected to the Kalamazoo River. All parties, including Consumers, that were asked to participate in the removal action plan declined to accept liability. Until further information is received from the EPA, Consumers is unable to estimate a range of potential liability for cleanup of the river.

Based on its experience, Consumers estimates that its share of the total liability for known CERCLA sites will be between $3 million and $8 million. Various factors, including the number and creditworthiness of potentially responsible parties involved with each site, affect Consumers’ share of the total liability. At March 31, 2021, Consumers had a recorded liability of $3 million for its share of the total liability at these sites, the minimum amount in the range of its estimated probable CERCLA liability, as no amount in the range was considered a better estimate than any other amount.

The timing of payments related to Consumers’ remediation and other response activities at its CERCLA and NREPA sites is uncertain. Consumers periodically reviews these cost estimates. A change in the underlying assumptions, such as an increase in the number of sites, different remediation techniques, the nature and extent of contamination, and legal and regulatory requirements, could affect its estimates of NREPA and CERCLA liability.

Ludington PCB: In 1998, during routine maintenance activities, Consumers identified PCB as a component in certain paint, grout, and sealant materials at Ludington. Consumers removed part of the PCB material and replaced it with non‑PCB material. Consumers has had several communications with the EPA regarding this matter, but cannot predict the financial impact or outcome.

MCV PPA: In 2017, the MCV Partnership initiated arbitration against Consumers, asserting a breach of contract associated with the MCV PPA. In 2019, an arbitration panel issued an order concluding that the

MCV Partnership is not entitled to any damages associated with a claim against Consumers that was related to the Clean Air Act. In November 2020, the MCV Partnership and Consumers signed a settlement agreement resolving all remaining disputes between the parties, and filed the settlement and associated agreements with the MPSC for approval. In March 2021, the MPSC approved the settlement and associated agreements.

Consumers Gas Utility Contingencies

Gas Environmental Matters: Consumers expects to incur remediation and other response activity costs at a number of sites under NREPA. These sites include 23 former MGP facilities. Consumers operated the facilities on these sites for some part of their operating lives. For some of these sites, Consumers has no present ownership interest or may own only a portion of the original site.

At March 31, 2021, Consumers had a recorded liability of $56 million for its remaining obligations for these sites. This amount represents the present value of long-term projected costs, using a discount rate of 2.57 percent and an inflation rate of 2.5 percent. The undiscounted amount of the remaining obligation is $61 million. Consumers expects to pay the following amounts for remediation and other response activity costs during the remainder of 2021 and in each of the next five years:


In Millions
	2021			2022			2023			2024			2025			2026
Consumers
Remediation and other response activity costs		$	3		$	9		$	23		$	11		$	2		$	1

Consumers periodically reviews these cost estimates. Any significant change in the underlying assumptions, such as an increase in the number of sites, changes in remediation techniques, or legal and regulatory requirements, could affect Consumers’ estimates of annual response activity costs and the MGP liability.

Pursuant to orders issued by the MPSC, Consumers defers its MGP-related remediation costs and recovers them from its customers over a ten-year period. At March 31, 2021, Consumers had a regulatory asset of $118 million related to the MGP sites.

Consumers estimates that its liability to perform remediation and other response activities at NREPA sites other than the MGP sites could reach $3 million. At March 31, 2021, Consumers had a recorded liability of less than $1 million, the minimum amount in the range of its estimated probable liability, as no amount in the range was considered a better estimate than any other amount.

Ray Compressor Station: On January 30, 2019, Consumers experienced a fire at the Ray Compressor Station, which resulted in the Ray Storage Field being off‑line or operating at significantly reduced capacity, which negatively affected Consumers’ natural gas supply and delivery capacity. This incident, which occurred during the extreme polar vortex weather condition, required Consumers to request voluntary reductions in customer load, to implement contingency gas supply purchases, and to implement a curtailment of natural gas deliveries for industrial and large commercial customers pursuant to Consumers’ MPSC curtailment tariff. The curtailment and request for voluntary reductions of customer loads were canceled as of midnight, February 1, 2019. Consumers investigated the cause of the incident, and filed a report on the incident with the MPSC in April 2019. In response, the MPSC issued an order in July 2019, directing Consumers to file additional reports regarding the incident and to include detail of the resulting costs in a future rate proceeding. The compressor station is presently operating at full capacity.

In May 2020, the MPSC approved an administrative settlement agreement between Consumers and the MPSC Staff, which resulted in a $10,000 civil penalty in connection with the fire. Consumers may also be subject to various claims from impacted customers and claims for damages.

In September 2020, the MPSC disallowed the recovery of $7 million in incremental gas purchases related to the fire. In January 2021, the MPSC denied Consumers’ petition for a rehearing challenging this disallowance. In February 2021, Consumers filed an appeal of the MPSC’s denial with the Michigan Court of Appeals. Consumers could also be subject to disallowances of costs associated with the repair and modification of the Ray Compressor Station. At March 31, 2021, Consumers had incurred capital expenditures of $17 million to restore and modify the compressor station.

As of March 31, 2021, Consumers had recorded an insurance recovery of $10 million related to the compressor station; of this amount, $7 million represented recovery of the costs to repair the station and $3 million represented recovery of incremental gas purchases related to the fire. Consumers recognized $4 million of the insurance recovery as a reduction to plant, property, and equipment, $3 million as a reduction of maintenance and other operating expenses, and $3 million as operating revenue.

At this time, Consumers cannot predict the outcome of these matters or other gas-related incidents and a reasonable estimate of a total loss cannot be made, but they could have a material adverse effect on Consumers’ results of operations, financial condition, or liquidity, and could subject Consumers’ gas utility to increased regulatory scrutiny.

Guarantees

Presented in the following table are CMS Energy’s and Consumers’ guarantees at March 31, 2021:

In Millions

Guarantee Description

Issue Date

Expiration Date

Maximum Obligation

Carrying Amount

CMS Energy, including Consumers

Indemnity obligations from purchase of VIE1

September 2020

indefinite

$

341

$

—

Indemnity obligations from stock and asset sale agreements2

various

indefinite

153

2

Guarantee3

July 2011

indefinite

30

—

Consumers

Guarantee3

July 2011

indefinite

$

30

$

—

1In conjunction with the purchase of its interest in Aviator Wind Equity Holdings, CMS Enterprises assumed certain indemnity obligations that protect the associated tax equity investor against losses incurred as a result of breaches of representations and warranties provided by Aviator Wind Equity Holdings and its subsidiaries. These obligations are generally capped at an amount equal to the tax equity investor’s capital contributions plus a specified return, less any distributions and tax benefits it receives, in connection with its membership interest in Aviator Wind. CMS Enterprises would recover 49 percent of any amounts paid to the tax equity investor from the other owner of Aviator Wind Equity Holdings. Additionally, Aviator Wind holds insurance coverage that would partially protect against losses incurred as a result of certain failures to qualify for production tax credits. For further details on CMS Enterprises’ ownership interest in Aviator Wind Equity Holdings, see Note 13, Variable Interest Entities.

2These obligations arose from stock and asset sale agreements under which CMS Energy or a subsidiary of CMS Energy indemnified the purchaser for losses resulting from various matters, primarily claims related to taxes. The maximum obligation amount is mostly related to the Equatorial Guinea tax claim discussed in

the CMS Energy Contingencies section of this Note. CMS Energy believes the likelihood of material loss to be remote for the indemnity obligations not recorded as liabilities.

3This obligation comprises a guarantee provided by Consumers to the U.S. Department of Energy in connection with a settlement agreement regarding damages resulting from the department’s failure to accept spent nuclear fuel from nuclear power plants formerly owned by Consumers.

Additionally, in the normal course of business, CMS Energy, Consumers, and certain other subsidiaries of CMS Energy have entered into various agreements containing tax and other indemnity provisions for which they are unable to estimate the maximum potential obligation. The carrying value of these indemnity obligations is $1 million. CMS Energy and Consumers consider the likelihood that they would be required to perform or incur substantial losses related to these indemnities to be remote.

Other Contingencies

In addition to the matters disclosed in this Note and Note 1, Regulatory Matters, there are certain other lawsuits and administrative proceedings before various courts and governmental agencies, as well as unasserted claims that may result in such proceedings, arising in the ordinary course of business to which CMS Energy, Consumers, and certain other subsidiaries of CMS Energy are parties. These other lawsuits, proceedings, and unasserted claims may involve personal injury, property damage, contracts, environmental matters, federal and state taxes, rates, licensing, employment, and other matters. Further, CMS Energy and Consumers occasionally self-report certain regulatory non‑compliance matters that may or may not eventually result in administrative proceedings. CMS Energy and Consumers believe that the outcome of any one of these proceedings and potential claims will not have a material negative effect on their consolidated results of operations, financial condition, or liquidity.

Consumers Energy Company

Other Commitments [Line Items]

Contingencies and Commitments

CMS Energy and Consumers are involved in various matters that give rise to contingent liabilities. Depending on the specific issues, the resolution of these contingencies could negatively affect CMS Energy’s and Consumers’ liquidity, financial condition, and results of operations. In their disclosures of these matters, CMS Energy and Consumers provide an estimate of the possible loss or range of loss when such an estimate can be made. Disclosures that state that CMS Energy or Consumers cannot predict the outcome of a matter indicate that they are unable to estimate a possible loss or range of loss for the matter.

CMS Energy Contingencies

Bay Harbor: CMS Land retained environmental remediation obligations for the collection and treatment of leachate at Bay Harbor after selling its interests in the development in 2002. Leachate is produced when water enters into cement kiln dust piles left over from former cement plant operations at the site. In 2012, CMS Land and EGLE finalized an agreement that established the final remedies and the future water quality criteria at the site. CMS Land completed all construction necessary to implement the remedies required by the agreement and will continue to maintain and operate a system to discharge treated leachate into Little Traverse Bay under an NPDES permit, which was valid through September 2020. CMS Land submitted a renewal request for the permit in April 2020. CMS Land is allowed to continue operating under the previous NPDES permit until a response is received from EGLE.

At March 31, 2021, CMS Energy had a recorded liability of $45 million for its remaining obligations for environmental remediation. CMS Energy calculated this liability based on discounted projected costs, using a discount rate of 4.34 percent and an inflation rate of one percent on annual operating and maintenance costs. The undiscounted amount of the remaining obligation is $56 million. CMS Energy expects to pay the following amounts for long-term leachate disposal and operating and maintenance costs during the remainder of 2021 and in each of the next five years:


In Millions
	2021			2022			2023			2024			2025			2026
CMS Energy
Long-term leachate disposal and operating and maintenance costs		$	3		$	4		$	4		$	4		$	4		$	4