CT-1040: Connecticut Resident Income Tax Return (2025)
Connecticut · Connecticut DRS · Used for tax years 2025
Form CT-1040 is the 2025 Connecticut Resident Income Tax Return. It reports federal adjusted gross income, Connecticut income adjustments, taxes, credits, withholding, and payments to calculate your refund or total amount due.
When it's due
The due date for the 2025 Connecticut Form CT-1040 is April 15, 2026.
What you'll need
Have these forms and details available, as applicable:
- Your federal Form 1040 or Form 1040-SR. Connecticut Line 1 uses federal adjusted gross income from Line 11a.
- Your Social Security number, name, mailing address, and spouse’s information for a joint return.
- Forms W-2 and 1099 showing Connecticut income tax withheld. Use them to complete the withholding schedule, but do not send them with your return. Do not send Schedules CT K-1 either.
- Your 2025 estimated tax payments, prior-year overpayments applied, and payments made with Form CT-1040 EXT.
- Applicable schedules and forms supporting adjustments and credits. Attach copies to your return.
- A copy of the return filed with each qualifying jurisdiction if claiming the Schedule 2 credit for income taxes paid there.
- Property descriptions, tax town or district, payment dates, and amounts paid if completing Schedule 3 for the property tax credit.
- Bank routing and account numbers if requesting direct deposit. Direct deposit is not available to first-time filers.
Complete Schedule CT-Dependent if you claimed dependents on your federal Form 1040.
How to file
File electronically
File and pay through myconneCT at portal.ct.gov/DRS-myconneCT.
File by mail
Use the 2025 form, complete it in blue or black ink, and enter whole-dollar amounts. Complete applicable schedules and send all four pages with required attachments. Sign the declaration. Your spouse must also sign a joint return. Do not use staples.
Returns requesting a refund and all other returns without payment:
Department of Revenue Services
PO Box 2976
Hartford CT 06104-2976
Returns with payment:
Department of Revenue Services
PO Box 2977
Hartford CT 06104-2977
Make your check payable to Commissioner of Revenue Services. Write “2025 Form CT-1040” on the check. Adding your Social Security number or numbers is optional. Clip the check to the return where indicated.
Keep a copy of your return for your records.
Common mistakes
- Using the wrong year’s form. The form warns that this can delay processing.
- Leaving the withholding schedule incomplete. Complete Columns A, B, and C or your withholding will be disallowed. Only enter W-2 and 1099 information if Connecticut income tax was withheld.
- Missing credit attachments. The property tax credit requires completed Schedule 3. The credit for taxes paid to qualifying jurisdictions requires copies of those returns. The form warns that these credits will be disallowed without the required attachments. Schedule CT-PE must also be attached when claiming the Pass-Through Entity Tax Credit.
- Sending only part of the return. Send all four pages and applicable attachments, but do not send Forms W-2, Forms 1099, or Schedules CT K-1.
- Using the wrong mailing address. Returns with payment and returns without payment go to different PO boxes.
- Leaving use tax blank when none is due. Enter “0” on Lines 69 and 15 if no use tax is due.
- Including out-of-state income as an “other” subtraction. Schedule 1, Line 49 specifically says not to include it.
Questions people ask
Can I get my refund by direct deposit?
Yes, unless you are a first-time filer. Complete Lines 25a, 25b, and 25c. Without 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. Enter the amount you want applied to your 2026 estimated tax on Line 23.
Do I need to report use tax on online purchases?
The form directs you to check for use tax on online or other purchases where you paid no sales tax. Complete the Connecticut Individual Use Tax Worksheet to calculate the tax, then report it through Schedule 4.
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 to authorize DRS to contact that person about your return.