CT-1040: Connecticut Resident Income Tax Return (2024)
Connecticut · Connecticut DRS · Used for tax years 2024
Form CT-1040 is the Connecticut Resident Income Tax Return for 2024. It reports federal adjusted gross income, Connecticut income adjustments, taxes, credits, withholding, and payments to calculate a refund or total amount due.
When it's due
The due date for the 2024 Connecticut Form CT-1040 is April 15, 2025.
What you'll need
Have these documents and details available, as applicable:
- Federal Form 1040 or 1040-SR: Line 11 provides the federal adjusted gross income entered on this return.
- Forms W-2 and 1099 showing Connecticut income tax withheld: Use these to complete the withholding information. Do not send Forms W-2 or 1099, or Schedules CT K-1, with the return.
- Applicable schedules and forms: Attach copies to your return. Complete Schedule CT-Dependent if you claimed dependents on your federal Form 1040.
- A copy of the return filed with each qualifying jurisdiction: Required if claiming the Schedule 2 credit for income taxes paid to qualifying jurisdictions.
- Property tax details: Schedule 3 asks for the Connecticut tax town or district, property description, payment dates, and amounts paid.
- Payment information: The return asks for 2024 estimated tax payments, prior-year overpayments applied, and payments made with Form CT-1040 EXT.
- Bank routing and account numbers: Needed if requesting direct deposit, which is not available to first-time filers.
How to file
File electronically
File and pay using myconneCT at portal.ct.gov/DRS-myconneCT.
File by mail
Complete the return in blue or black ink, using whole dollars only. Complete applicable schedules, attach applicable forms, and send all four pages to DRS. Sign the declaration on page 2. For a joint return, your spouse must also sign. Keep a copy for your records.
For refunds and all other returns without payment:
Department of Revenue Services
PO Box 2976
Hartford CT 06104-2976
For returns with payment:
Department of Revenue Services
PO Box 2977
Hartford CT 06104-2977
Make your check payable to Commissioner of Revenue Services. Write “2024 Form CT-1040” on the check. Including your Social Security number(s) is optional. Clip the check to the return where indicated. Do not use staples.
Common mistakes
- Using the wrong year's form: DRS warns that the correct year's form must be submitted to avoid processing delays.
- Sending an incomplete return: Complete applicable schedules and send all four pages. Remember to sign the declaration.
- Leaving withholding columns blank: Complete Columns A, B, and C of the withholding schedule or your withholding will be disallowed. Only enter W-2 and 1099 information if Connecticut income tax was withheld.
- Missing required credit attachments: The property tax credit will be disallowed without completed Schedule 3. The credit for taxes paid to qualifying jurisdictions will be disallowed without copies of those returns. Schedule CT-PE must be attached when claiming the Pass-Through Entity Tax Credit.
- Subtracting out-of-state income on Schedule 1, Line 49: The form specifically says not to include it there.
- Leaving use tax blank when none is due: Enter “0” on Schedule 4, Line 69, and on Line 15.
- Using the wrong mailing address: Use the address that matches whether your return includes a payment.
- Sending documents the form says not to send: Do not include Forms W-2 or 1099, or Schedules CT K-1. Do not use staples.
Questions people ask
Can I receive my refund by direct deposit?
Yes, unless you are a first-time filer. Complete Lines 25a, 25b, and 25c for direct deposit. If you do not elect direct deposit, a refund check will be issued and processing may be delayed.
Can I apply an overpayment to next year's estimated tax?
Yes. Line 23 lets you apply part or all of your Line 22 overpayment to your 2025 estimated tax.
What does the form charge for a late payment?
Line 27 calculates a penalty of 10% of the tax due on Line 26. Line 28 calculates interest at 1% of that tax due for each month or fraction of a month late.
Can I authorize someone else to discuss my return with DRS?
Yes. Complete the Third Party Designee section with the person's name, telephone number, and personal identification number (PIN) to authorize DRS to contact that person about the return.