CT-1040 EXT: Application for Extension of Time to File Connecticut Income Tax Return for Individuals (2025)
Connecticut · Connecticut DRS · Used for tax years 2025
Form CT-1040 EXT requests a six-month extension to file your 2025 Connecticut individual income tax return and individual use tax. It reports expected tax liabilities, withholding, estimated payments, the Pass-Through Entity Tax Credit, and any amount due. It extends the time to
Who files this form
Use Form CT-1040 EXT to request a six-month extension to file your Connecticut individual income tax return. It also extends the time to file your individual use tax.
- You do not need to file this form if you requested a federal filing extension for 2025 and expect to owe no additional Connecticut income tax after withholding, estimated payments, and any Pass-Through Entity Tax Credit. DRS automatically grants a six-month filing extension.
- If you did not request a federal filing extension, you must file CT-1040 EXT to request a Connecticut extension, even if you owe no additional Connecticut income tax. You must explain your good cause for the request.
- The form specifically requires filing if you qualify as an out-of-country taxpayer for federal filing purposes. Generally, this includes U.S. citizens or residents living and working outside the U.S. and Puerto Rico, or military or naval personnel on duty outside those areas who cannot file a timely Connecticut return. Explain your status and qualification for the automatic two-month federal extension on the front of the form.
When it's due
For calendar-year 2025 taxpayers:
- April 15, 2026: File Form CT-1040 EXT and pay the balance due to avoid penalty and interest.
- October 15, 2026: Extended deadline to file the 2025 Connecticut income tax return.
This extension gives you more time to file, not more time to pay.
What you'll need
Have the following information ready:
- Your name, complete Social Security number, address, and daytime telephone number. For a joint return, include your spouse’s name and complete Social Security number.
- Your expected 2025 Connecticut income tax and individual use tax liabilities.
- Connecticut income tax withheld, 2025 estimated Connecticut income tax payments, any 2024 overpayment applied to 2025, and your 2025 Pass-Through Entity Tax Credit.
- Whether you requested a federal extension on Form 4868. If not, provide a reason for your Connecticut extension request.
- Your tax-year beginning and ending dates and requested extension date if you are not a calendar-year taxpayer.
Do not attach W-2s or 1099s.
How to file
Complete the entire form and pay the amount on Line 7. A signature is not required on this form.
Online: File and pay electronically through DRS myconneCT. The form lists portal.ct.gov/DRS for more information.
Credit or debit card: You may pay your expected 2025 tax liability by credit card or comparable debit card. A convenience fee applies. Keep the confirmation number. Do not send Form CT-1040 EXT if you pay by credit card.
By mail 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 EXT” on the check; adding your Social Security number(s) is optional. Sign the check and paper clip it to the front of the form. Do not send cash.
By mail without payment:
Department of Revenue Services
PO Box 2976
Hartford CT 06104-2976
Do not mail this form if you owe no tax and have requested an extension to file your 2025 federal income tax return.
Common mistakes
- Treating this as a payment extension. Tax must be paid by the original due date. Unpaid tax is subject to interest and may be subject to a penalty.
- Filing the extension request late. The form warns that requests filed after the original return due date will be denied.
- Leaving Lines 1 or 2 blank. Enter an amount on each line, including “0” if you expect no liability for that tax.
- Leaving out complete Social Security numbers. They are required on the form, even though they are optional on your check.
- Using the wrong year’s form. Use the 2025 form to avoid processing delays.
- Ignoring paper-form directions. Type or print in blue or black ink only. Do not use staples or attach W-2s or 1099s.
- Assuming an electronic payment replaces the return. You must still file your tax return by its due date.
Questions people ask
Can I request a Connecticut extension without a federal extension?
Yes. You must have good cause and explain why you are requesting the Connecticut extension.
Will DRS confirm that my request was approved?
DRS will notify you only if your request is denied.
Do I need to sign Form CT-1040 EXT?
No. Your signature is not required on this form. If you pay by check, you must sign the check.
Can I request more time to pay?
You may qualify for a six-month payment extension. To request it, file Form CT-1127, Application for Extension of Time for Payment of Income Tax, with your timely filed Connecticut income tax return or extension.
What charges can apply if I pay late?
The form states that interest is 1% per month or part of a month on unpaid tax, from the original due date until payment. The late-payment penalty is 10% of the tax not paid by the original due date.