Version: 2.0.0

Update

Use this endpoint to update the information on existing CT-941 forms that are already created for a specific payer.

You cannot update a return once it has been transmitted.

PUT StateFilings/CT941WH/Update

Run in Postman

Request Body

Field	Type	Description
SubmissionId	Guid	Unique identifier created by TaxBandits for each submission.
StateWHRecords	Object[]	Object to identify the records.
SequenceId	String	A unique identifier for this record. Size Range: ..50
RecordId	Guid	A unique identifier generated by TaxBandits when a Form CT-941 return is created.
ReturnHeader	Object	Contains business information.
TaxYear	String	The tax year for which the Form CT-941 is to be filed. Allowed values 2025,2026
Qtr	String	The quarter for which the Form CT-941 is to be filed. Allowed values "Q1", "Q2", "Q3", "Q4"
Business	object	Object to identify the Business Details.
BusinessId	Guid	Optional Use the unique Business ID (Generated by TaxBandits) that you received in the response of the Business CREATE Endpoint. If you do not have a Business ID, ignore the field. By giving the Business ID, you do not have to provide all the business information again.
PayerRef	string	Optional Your unique identifier for the payer. Can replace BusinessId in future requests. Size Range: 50
IsDefaultBusiness	Boolean	When set to TRUE, this business will be set as the default across requests that do not specify a business.
TINDetails	object	TIN information for the business.
Format	string	Specifies how the TIN is passed. Allowed values "PLAIN_TIN" — Pass TIN directly, "TOKENIZED_TIN" — Pass tokenized TIN
TINType	string	Specify the TIN type of the business. Allowed values "EIN", "SSN", "QI-EIN", "ITIN", "WP-EIN", "WT-EIN", "NQI-EIN", "IRSN"
TIN	string	The TIN value according to the Format selected.
IndividualNm	object	Optional Required when TINType is SSN. Provide individual name fields instead of BusinessNm.
FirstNm	string	The first name of the individual. Size Range: 20
MiddleNm	string	Optional Middle name of the individual. Size Range: 20
LastNm	string	The last name of the individual. Size Range: 20
Suffix	string	Optional Suffix of the individual's name. Allowed values "Jr", "Sr", "I", "II", "III", "IV", "V", "VI", "VII"
BusinessNm	string	Legal name of the business. Required when TINType is EIN. Size Range: 75
NameCtrl	string	Name control of the business as registered with the IRS. Size Range: 3-4
DBADetails	object[]	Optional DBA (Doing Business As) information.
DBANm	string	Name of the DBA. Size Range: 75
DBARef	string	Unique identifier for the DBA. Size Range: 1-50
DBAId	Guid	TaxBandits-generated DBA identifier.
Address	object[]	Address information of the DBA.
Address1	string	Street address or PO Box. Size Range: 46
Address2	string	Optional Suite or apartment number. Size Range: 46
City	string	DBA's city. Size Range: 50
ProvinceOrState	string	DBA's province or state name. When the country code is US: Allowed values "AL", "AK", "AZ", "AR", "CA", "CO", "CT", "DE", "DC", "FL", "GA", "HI", "ID", "IL", "IN", "IA", "KS", "KY", "LA", "ME", "MD", "MA", "MI", "MN", "MS", "MO", "MT", "NE", "NV", "NH", "NJ", "NM", "NY", "NC", "ND", "OH", "OK", "OR", "PA", "RI", "SC", "SD", "TN", "TX", "UT", "VT", "VA", "WA", "WV", "WI", "WY", "AS", "FM", "GU", "MH", "MP", "PW", "PR", "VI", "AA", "AE", "AP" When the country code is CA: Allowed values "AB", "BC", "MB", "NB", "NL", "NT", "NS", "NU", "ON", "PE", "QC", "SK", "YT" Note: The size range is set to 50 for all countries except the United States and Canada.
Zipcd	string	DBA's ZIP code. Size Range: 5-16
Country	string	DBA's 2-character country code. Allowed values "US","AF", "AX", "AL", "AG", "AQ", "AN", "AO", "AV", "AY", "AC", "AR", "AM", "AA", "AT", "AS", "AU", "AJ", "BF", "BA", "FQ", "BG", "BB", "BO", "BE", "BH", "BN", "BD", "BT", "BL", "BK", "BC", "BV", "BR", "IO", "VI", "BX", "BU", "UV", "BM", "BY", "CB", "CM", "CA", "CV", "CJ", "CT", "CD", "CI", "CH", "KT", "IP", "CK", "CO", "CN", "CF", "CG", "CW", "CR", "CS", "IV", "HR", "CU", "UC", "CY", "EZ", "DA", "DX", "DJ", "DO", "DR", "TT", "EC", "EG", "ES", "EK", "ER", "EN", "ET", "FK", "FO", "FM", "FJ", "FI", "FR", "FP", "FS", "GB", "GA", "GG", "GM", "GH", "GI", "GR", "GL", "GJ", "GQ", "GT", "GK", "GV", "PU", "GY", "HA", "HM", "VT", "HO", "HK", "HQ", "HU", "IC", "IN", "ID", "IR", "IZ", "EI", "IS", "IT", "JM", "JN", "JA", "DQ", "JE", "JQ", "JO", "KZ", "KE", "KQ", "KR", "KN", "KS", "KV", "KU", "KG", "LA", "LG", "LE", "LT", "LI", "LY", "LS", "LH", "LU", "MC", "MK", "MA", "MI", "MY", "MV", "ML", "MT", "IM", "RM", "MR", "MP", "MX", "MQ", "MD", "MN", "MG", "MJ", "MH", "MO", "MZ", "WA", "NR", "BQ", "NP", "NL", "NC", "NZ", "NU", "NG", "NI", "NE", "NF", "CQ", "NO", "MU", "OC", "PK", "PS", "LQ", "PM", "PP", "PF", "PA", "PE", "RP", "PC", "PL", "PO", "RQ", "QA", "RO", "RS", "RW", "TB", "RN", "WS", "SM", "TP", "SA", "SG", "RI", "SE", "SL", "SN", "NN", "LO", "SI", "BP", "SO", "SF", "SX", "OD", "SP", "PG", "CE", "SH", "SC", "ST", "SB", "VC", "SU", "NS", "SV", "WZ", "SW", "SZ", "SY", "TW", "TI", "TZ", "TH", "TO", "TL", "TN", "TD", "TS", "TU", "TX", "TK", "TV", "UG", "UP", "AE", "UK", "UY", "UZ", "NH", "VE", "VM", "VQ", "WQ", "WF", "WI", "YM", "ZA", "ZI"
Email	string	Optional Email address of the Business. Size Range: ..100
Address	object	Primary address of the business.
Address1	string	Street address or PO Box of the business. Size Range: 46
Address2	string	Optional Suite or apartment number of the business. Size Range: 46
City	string	City of the business. Size Range: 50
ProvinceOrState	string	Province or state name of the business. When the country code is US: Allowed values "AL", "AK", "AZ", "AR", "CA", "CO", "CT", "DE", "DC", "FL", "GA", "HI", "ID", "IL", "IN", "IA", "KS", "KY", "LA", "ME", "MD", "MA", "MI", "MN", "MS", "MO", "MT", "NE", "NV", "NH", "NJ", "NM", "NY", "NC", "ND", "OH", "OK", "OR", "PA", "RI", "SC", "SD", "TN", "TX", "UT", "VT", "VA", "WA", "WV", "WI", "WY", "AS", "FM", "GU", "MH", "MP", "PW", "PR", "VI", "AA", "AE", "AP" When the country code is CA: Allowed values "AB", "BC", "MB", "NB", "NL", "NT", "NS", "NU", "ON", "PE", "QC", "SK", "YT" Note: The size range is set to 50 for all countries except the United States and Canada.
ZipCd	string	ZIP code of the business. Size Range: 5-16
Country	string	2-character country code of the business. Allowed values "US","AF", "AX", "AL", "AG", "AQ", "AN", "AO", "AV", "AY", "AC", "AR", "AM", "AA", "AT", "AS", "AU", "AJ", "BF", "BA", "FQ", "BG", "BB", "BO", "BE", "BH", "BN", "BD", "BT", "BL", "BK", "BC", "BV", "BR", "IO", "VI", "BX", "BU", "UV", "BM", "BY", "CB", "CM", "CA", "CV", "CJ", "CT", "CD", "CI", "CH", "KT", "IP", "CK", "CO", "CN", "CF", "CG", "CW", "CR", "CS", "IV", "HR", "CU", "UC", "CY", "EZ", "DA", "DX", "DJ", "DO", "DR", "TT", "EC", "EG", "ES", "EK", "ER", "EN", "ET", "FK", "FO", "FM", "FJ", "FI", "FR", "FP", "FS", "GB", "GA", "GG", "GM", "GH", "GI", "GR", "GL", "GJ", "GQ", "GT", "GK", "GV", "PU", "GY", "HA", "HM", "VT", "HO", "HK", "HQ", "HU", "IC", "IN", "ID", "IR", "IZ", "EI", "IS", "IT", "JM", "JN", "JA", "DQ", "JE", "JQ", "JO", "KZ", "KE", "KQ", "KR", "KN", "KS", "KV", "KU", "KG", "LA", "LG", "LE", "LT", "LI", "LY", "LS", "LH", "LU", "MC", "MK", "MA", "MI", "MY", "MV", "ML", "MT", "IM", "RM", "MR", "MP", "MX", "MQ", "MD", "MN", "MG", "MJ", "MH", "MO", "MZ", "WA", "NR", "BQ", "NP", "NL", "NC", "NZ", "NU", "NG", "NI", "NE", "NF", "CQ", "NO", "MU", "OC", "PK", "PS", "LQ", "PM", "PP", "PF", "PA", "PE", "RP", "PC", "PL", "PO", "RQ", "QA", "RO", "RS", "RW", "TB", "RN", "WS", "SM", "TP", "SA", "SG", "RI", "SE", "SL", "SN", "NN", "LO", "SI", "BP", "SO", "SF", "SX", "OD", "SP", "PG", "CE", "SH", "SC", "ST", "SB", "VC", "SU", "NS", "SV", "WZ", "SW", "SZ", "SY", "TW", "TI", "TZ", "TH", "TO", "TL", "TN", "TD", "TS", "TU", "TX", "TK", "TV", "UG", "UP", "AE", "UK", "UY", "UZ", "NH", "VE", "VM", "VQ", "WQ", "WF", "WI", "YM", "ZA", "ZI"
ContactDetails	object[]	Details of the person the IRS can contact regarding the given business.
FirstNm	string	First name of the contact person. Size Range: 20
MiddleNm	string	Optional Middle name of the contact person. Size Range: 20
LastNm	string	Last name of the contact person. Size Range: 20
Suffix	string	Optional The suffix of the contact person. Allowed values "Jr", "Sr", "I", "II", "III", "IV", "V", "VI", "VII"
Phone	string	Optional Phone number of the contact person. Size Range: 10 digits
PhoneExtn	string	Optional Phone extension number. Size Range: 5
Email	string	Optional Email address of the contact person. Size Range: ..100
Fax	string	Optional Fax number of the contact person. Size Range: 10 digits
SigningAuthority	Object	Details of the person authorized to sign the return.
FirstNm	String	First name of the signatory. Size Range: 20
MiddleNm	String	Optional Middle name of the signatory. Size Range: 20
LastNm	String	Last name of the signatory. Size Range: 20
Suffix	String	Optional The suffix of the signatory. Allowed values "Jr", "Sr", "I", "II", "III", "IV", "V", "VI", "VII"
Phone	String	Optional Phone number of the signatory. Size Range: 10 digits
PhoneExtn	String	Optional Phone extension number of the signatory. Size Range: 5
BusinessMemberType	String	Optional Title or role of the signatory. Allowed values "CORPORATESECRETARY", "SECRETARYTREASURER", "PARTNER", "GENERALPARTNER", "LIMITEDPARTNER", "LLCMEMBER", "MANAGINGMEMBER", "MANAGER", "TAXMATTERPARTNER", "PRESIDENT", "VICEPRESIDENT", "CORPORATETREASURER", "TREASURER", "ASSISTANTTREASURER", "CHIEFACCOUNTINGOFFICER", "CHIEFEXECUTIVEOFFICER", "CHIEFFINANCIALOFFICER", "TAXOFFICER", "CHIEFOPERATINGOFFICER", "CORPORATEOFFICER", "EXECUTIVEDIRECTOR", "DIRECTOR", "CHAIRMAN", "EXECUTIVEADMINISTRATOR", "RECEIVER", "PASTOR", "ASSISTANTTORELIGIOUSLEADER", "REVEREND", "PRIEST", "MINISTER", "RABBI", "LEADEROFRELIGIOUSORGANIZATION", "SECRETARY", "DIRECTOROFTAXATION", "DIRECTOROFPERSONNEL", "ADMINISTRATOR", "EXECUTOR", "TRUSTEE", "FIDUCIARY", "OWNER", "SOLEPROPRIETOR", "MEMBER", "SOLEMEMBER", "REPORTINGAGENT"
ReturnData	Object[]	Identifies the Form CT-941 data.
FormCT941	Object	Connecticut withholding tax return.
WHIdNum	String	Connecticut withholding ID number. Size Range: ..13
IsFinalReturn	Boolean	Optional If true identifies that the payer no longer has any employees and no payroll has been carried forward.
OperationCeasedDt	String	Optional Date when the last payroll was processed. Enter the date in the format: MM/DD/YYYY or MM-DD-YYYY. Example: 01/25/2026
TotWages	Number	Gross wages paid for the quarter. Size Range: 0-9999999999.99
TotCTWages	Number	Gross wages paid subject to Connecticut withholding for the quarter. Size Range: 0-9999999999.99
TotTaxWH	Number	Connecticut tax withheld for the quarter. Size Range: 0-9999999999.99
Overpayment	Number	Overpayment Credit from prior quarter. Size Range: 0-9999999999.99
TotTaxPaid	Number	Payments made for this quarter. Size Range: 0-9999999999.99
TotPayment	Number	Total payments from tax withheld and overpayment Credit from prior quarter. Size Range: 0-9999999999.99
TotWHDue	Number	Net tax due for the quarter. Size Range: -9999999999.99 to 9999999999.99 Note: If this amount is a negative number, use a minus sign.
Penalty	Number	Penalty for the quarter. Size Range: 0-9999999999.99
Interest	Number	Interest due for the quarter. Size Range: 0-9999999999.99
TotPenaltyInterest	Number	Total penalties and interest due amount. Size Range: 0-9999999999.99
Credit	Number	Amount to be credited. Size Range: 0-9999999999.99
Refund	Number	Amount to be refunded. Size Range: 0-9999999999.99
BalanceDue	Number	Total tax amount due. Size Range: 0-9999999999.99
PayPeriod	Object[]	Object that contains tax liability details for the quarter.
PayDate	String	Date when the payment was made. Enter the date in the format: MM/DD/YYYY or MM-DD-YYYY. Example: 01/25/2026
Month1Amt	Number	Liability amount for first month of the quarter. Size Range: 0-9999999999.99
Month2Amt	Number	Liability amount for second month of the quarter. Size Range: 0-9999999999.99
Month3Amt	Number	Liability amount for third month of the quarter. Size Range: 0-9999999999.99
TotMonth1TaxLiab	Number	Total tax liability for the first month of the quarter. Size Range: 0-9999999999.99
TotMonth2TaxLiab	Number	Total tax liability for the second month of the quarter. Size Range: 0-9999999999.99
TotMonth3TaxLiab	Number	Total tax liability for the third month of the quarter. Size Range: 0-9999999999.99
TotTaxLiab	Number	Total tax liability for the quarter. Size Range: 0-9999999999.99
StatePayment	Object	Optional Object that contains information about the payment details.
PaymentAmt	Number	Amount to be paid. Size Range: 0-9999999999.99
BankRoutingNum	string	Bank Routing Number of payment. Size Range: 9
BankAccountNum	string	Bank Account Number for payment. Size Range: ..17
AccountType	string	Bank account type. Allowed values "Checking", "Saving"
PaymentReqDate	String	Date when the payment has to be made. Enter the date in the format: MM/DD/YYYY or MM-DD-YYYY. Example: 01/25/2026
StateRefundAccount	Object	Optional Object that contains information about the refund account details.
AccountType	string	Bank account type. Allowed values "Checking", "Saving"
BankRoutingNum	string	Bank Routing Number of payment. Size Range: 9
BankAccountNum	string	Bank Account Number for payment. Size Range: ..17
IsForeignBankAcc	Boolean	Optional If true identifies that provided account details belong to a foreign account.

Response Body

Field	Type	Description
SubmissionId	Guid	Unique identifier of a submission.
SuccessRecords	object[]	It will show the detailed information about the success status of Form CT-941 records.
SequenceId	string	Returns the unique reference ID for the submission that can be used to identify a particular record.
BusinessId	Guid	Unique identifier of a business.
PayerRef	string	Unique identifier of the payer.
RecordId	Guid	A unique identifier generated by TaxBandits when a CT-941 return is created.
FormType	string	Denotes the type of withholding form (Form CT-941).
Status	string	Returns the record status of the return.
StatusTs	string	Returns the date and time when the return was created.
Info	string	Returns additional information about the return.
Errors	object[]	Displays error information related to the state returns of Form CT-941.
Id	string	Returns the validation error ID.
Name	string	Name of the validation error.
ErrorRecords	object[]	Provides detailed information about the error status of Form CT-941 records.
SequenceId	string	A unique reference ID for the submission that can be used to identify a particular record. The Sequence ID will be returned in the response for your reference.
RecordId	Guid	Unique identifier for the record.
Errors	object[]	Displays detailed error information.
Id	string	Returns the validation error ID.
Name	string	Name of the validation error.
Message	string	Description of the validation error.

Request JSON

{
"SubmissionId": "01a0e708-6408-76cc-94a2-ea3dada33b43",
"StateWHRecords": [
  {
    "SequenceId": "001",
    "RecordId": "01a0e708-673c-716b-ac6d-bad8ee63096e",
    "ReturnHeader": {
      "Qtr": "Q3",
      "TaxYear": "2026",
      "Business": {
        "BusinessId": null,
        "PayerRef": null,
        "IsDefaultBusiness": true,
        "TINDetails": {
          "Format": "PLAIN_TIN",
          "TINType": "EIN",
          "TIN": "45-9875855"
        },
        "IndividualNm": {
          "FirstNm": "James",
          "MiddleNm": "A",
          "LastNm": "Anderson",
          "Suffix": "Jr"
        },
        "BusinessNm": "Snowdaze LLC",
        "NameCtrl": "SNOW",
        "DBADetails": {
          "DBANm": "Iceberg Icecreams",
          "DBARef": "DBA1001",
          "DBAId": null,
          "Address": {
            "Address1": "123 Main St",
            "Address2": "Suite 1001",
            "City": "Rock Hill",
            "ProvinceOrState": "SC",
            "ZipCd": "29730",
            "Country": "US"
          }
        },
        "Address": {
          "Address1": "123 Main St",
          "Address2": "Suite 1001",
          "City": "Rock Hill",
          "ProvinceOrState": "SC",
          "ZipCd": "29730",
          "Country": "US"
        },
        "ContactDetails": {
          "FirstNm": "James",
          "MiddleNm": "A",
          "LastNm": "Anderson",
          "Suffix": "Jr",
          "Phone": "8035551234",
          "PhoneExtn": "101",
          "Email": "contact@snowdaze.com",
          "Fax": "8035555678"
        },
        "BusinessType": "ESTE",
        "SigningAuthority": {
          "FirstNm": "Ambrane",
          "MiddleNm": "A",
          "LastNm": "Cavil",
          "Suffix": "Jr",
          "Phone": "8035551000",
          "PhoneExtn": "111",
          "BusinessMemberType": "ADMINISTRATOR"
        }
      }
    },
    "ReturnData": {
      "FormCT941": {
        "WHIdNum": "64535450-000",
        "IsNoPayroll": false,
        "OperationCeasedDt": "12/21/2025",
        "TotWages": "1000",
        "TotCTWages": "500",
        "TotTaxWH": "400",
        "Overpayment": "500",
        "TotTaxPaid": "100",
        "TotPayment": "600",
        "TotWHDue": "-200",
        "Penalty": "0",
        "Interest": "0",
        "TotPenaltyInterest": "0",
        "Credit": "200",
        "Refund": "0",
        "BalanceDue": "200",
        "PayPeriod": [
          {
            "PayDate": "08/20/2025",
            "Month1Amt": "400",
            "Month2Amt": "0",
            "Month3Amt": "0"
          }
        ],
        "TotMonth1TaxLiab": "400",
        "TotMonth2TaxLiab": "0",
        "TotMonth3TaxLiab": "0",
        "TotTaxLiab": "400"
      },
      "StatePayment": {
        "PaymentAmt": "200",
        "BankRoutingNum": "217555555",
        "BankAccountNum": "0000000001",
        "AccountType": "Checking",
        "PaymentReqDate": "12/31/2026"
      },
      "StateRefundAccount": {
        "AccountType": "SAVING",
        "BankRoutingNum": "017443944",
        "BankAccountNum": "1279065890",
        "IsForeignBankAcc": false
      }
    }
  }
]
}

Response JSON

Success Response - This is a sample response for successful API requests.

{
  "SubmissionId": "01a0e708-6408-76cc-94a2-ea3dada33b43",
  "SuccessRecords": [
      {
          "SequenceId": "001",
          "BusinessId": "68f604f3-3ae4-4ffa-9e9e-8ad79de7ece4",
          "PayerRef": null,
          "RecordId": "01a0e708-673c-716b-ac6d-bad8ee63096e",
          "FormType": "CT941WH",
          "Status": "CREATED",
          "StatusTs": "2026-09-28 04:03:53 -04:00",
          "Info": null,
          "Errors": null
      }
  ],
  "ErrorRecords": null,
  "Errors": null
}

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Response JSON