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| <?xml version="1.0" encoding="windows-1252"?> |
| <ownershipDocument> |
| <schemaVersion> X0306 </schemaVersion> |
| <documentType> 4 </documentType> |
| <periodOfReport> 2022-08-16 </periodOfReport> |
| <notSubjectToSection16> 0 </notSubjectToSection16> |
| <issuer> |
| | <issuerCik> 0000811156 </issuerCik> |
| | <issuerName> CMS ENERGY CORP </issuerName> |
| | <issuerTradingSymbol> CMS </issuerTradingSymbol> |
| | </issuer> |
| <reportingOwner> |
| | <reportingOwnerId> |
| | | <rptOwnerCik> 0001834917 </rptOwnerCik> |
| | | <rptOwnerName> Wells LeeRoy Jr </rptOwnerName> |
| | | </reportingOwnerId> |
| | <reportingOwnerAddress> |
| | | <rptOwnerStreet1> ONE ENERGY PLAZA </rptOwnerStreet1> |
| | | <rptOwnerStreet2></rptOwnerStreet2> |
| | | <rptOwnerCity> JACKSON </rptOwnerCity> |
| | | <rptOwnerState> MI </rptOwnerState> |
| | | <rptOwnerZipCode> 49201 </rptOwnerZipCode> |
| | | <rptOwnerStateDescription></rptOwnerStateDescription> |
| | | </reportingOwnerAddress> |
| | <reportingOwnerRelationship> |
| | | <isDirector> 0 </isDirector> |
| | | <isOfficer> 1 </isOfficer> |
| | | <isTenPercentOwner> 0 </isTenPercentOwner> |
| | | <isOther> 0 </isOther> |
| | | <officerTitle> Senior Vice President </officerTitle> |
| | | <otherText></otherText> |
| | | </reportingOwnerRelationship> |
| | </reportingOwner> |
| <nonDerivativeTable> |
| | <nonDerivativeTransaction> |
| | | <securityTitle> |
| <value> Common Stock </value> |
| </securityTitle> |
| | | <transactionDate> |
| <value> 2022-08-16 </value> |
| </transactionDate> |
| | | <transactionCoding> |
| <transactionFormType> 4 </transactionFormType> |
| <transactionCode> F </transactionCode> |
| <equitySwapInvolved> 0 </equitySwapInvolved> |
| </transactionCoding> |
| | | <transactionAmounts> |
| <transactionShares> |
| <value> 179 </value> |
| </transactionShares> |
| <transactionPricePerShare> |
| <value> 70.26 </value> |
| </transactionPricePerShare> |
| <transactionAcquiredDisposedCode> |
| <value> D </value> |
| </transactionAcquiredDisposedCode> |
| </transactionAmounts> |
| | | <postTransactionAmounts> |
| <sharesOwnedFollowingTransaction> |
| <value> 34226 </value> |
| </sharesOwnedFollowingTransaction> |
| </postTransactionAmounts> |
| | | <ownershipNature> |
| <directOrIndirectOwnership> |
| <value> D </value> |
| <footnoteId id="F1"/> |
| </directOrIndirectOwnership> |
| </ownershipNature> |
| | | </nonDerivativeTransaction> |
| | </nonDerivativeTable> |
| <derivativeTable></derivativeTable> |
| <footnotes> |
| | <footnote id="F1"> The total holdings reflect an adjustment of 107 additional shares of Common Stock of CMS Energy Corporation ("CMS") acquired as a result of dividend reinvestment pursuant to the reporting person's participation in the CMS Stock Purchase Plan, and an adjustment of 116 additional shares of Restricted Stock purchased on behalf of the reporting person as a result of automatic acquisition of Restricted Stock in lieu of cash dividends pursuant to the terms of the award granted to the reporting person in accordance with the provisions of the CMS Performance Incentive Stock Plan. </footnote> |
| | </footnotes> |
| <remarks></remarks> |
| <ownerSignature> |
| | <signatureName> Rhonda M. Morris, Attny-in-Fact </signatureName> |
| | <signatureDate> 2022-08-17 </signatureDate> |
| | </ownerSignature> |
| </ownershipDocument> |
