CT-1065/CT-1120SI EXT: Application for Extension of Time to File Connecticut Composite Income Tax Return (2025)
Connecticut · Connecticut DRS · Used for tax years 2025
Form CT-1065/CT-1120SI EXT requests a six-month extension to file the 2025 Connecticut Composite Income Tax Return and furnish Schedule CT K-1 to members. It reports the pass-through entity’s Connecticut composite income tax liability, which may be estimated. The extension does n
Who files this form
Partnerships and S corporations use Form CT-1065/CT-1120SI EXT to request a six-month extension to file their Connecticut Composite Income Tax Return, Form CT-1065/CT-1120SI. The extension also gives them the same additional time to furnish Schedule CT K-1 to members.
A federal extension does not automatically extend the Connecticut filing deadline. The pass-through entity must file this Connecticut extension form to request more time.
When it's due
- 2025 calendar-year extension request: File on or before March 15, 2026, as printed in the form instructions. If the due date falls on a Saturday, Sunday, or legal holiday, filing by the next business day is considered timely.
- 2025 calendar-year extended deadline: The form requests an extension to September 15, 2026, to file Form CT-1065/CT-1120SI and furnish Schedule CT K-1 to members.
This extension does not extend the time to pay tax. Pay the amount shown on Line 1 by the original return due date.
What you'll need
Have the following information ready to complete the form:
- The pass-through entity’s name, address, type, Federal Employer ID Number (FEIN), and Connecticut Tax Registration Number.
- The entity’s 2025 Connecticut composite income tax liability for Line 1. You may estimate it. Enter zero if no tax is due.
- Whether federal Form 7004 has been filed. If it has not, provide the reason for requesting the Connecticut extension.
- The taxable-year dates and requested extension date, if not filing for the calendar year.
- The general partner’s or corporate officer’s signature, title, date, and telephone number, plus paid preparer details if applicable.
- Bank account or credit or debit card information for an electronic payment.
How to file
File and pay electronically. Do not mail a paper return to DRS.
To file through myconneCT at portal.ct.gov/DRS-myconneCT:
- Log in and find your tax account on the Summary screen.
- Select File an Extension.
- Choose your payment method and file Form CT-1065/CT-1120SI EXT.
The instructions require an electronic payment at the time of filing through myconneCT. You can use direct payment from a checking or savings account, or pay by credit or debit card. Direct payment lets you select a withdrawal date up to the due date. Card payments carry a convenience fee, which is disclosed before you complete the transaction, and take effect on the date of the charge.
Keep the confirmation number and a copy of the form for your records.
Common mistakes
- Leaving Line 1 blank: An amount is required. Enter zero if no tax is due.
- Using the wrong year’s form: The form is year-specific. Use the correct year to avoid processing delays.
- Assuming a federal extension covers Connecticut: An IRS extension does not automatically extend the Connecticut filing date.
- Treating this as a payment extension: Tax not paid by the original due date may be subject to interest and penalties.
- Mailing the form or paying by check: Electronic filing and payment are required. If you pay through your financial institution’s online banking system, verify that it sends an electronic funds transfer (EFT), not a check.
Questions people ask
Do I need to explain why I want an extension?
If the entity has already filed federal Form 7004 with the IRS, no reason is needed for the Connecticut request. If Form 7004 was not filed, the entity may apply if there is reasonable cause and must explain its reason.
Will DRS confirm that my extension was approved?
DRS will notify you only if the extension request is denied.
Can I request more time to pay using this form?
No. This form only extends the time to file the return and furnish Schedule CT K-1. To request an extension of the payment due date, you must file Form CT-1127, Application for Extension of Time for Payment of Income Tax.
What happens if I pay late?
In general, interest applies to unpaid tax at 1% per month or fraction of a month until it is paid in full. The late payment penalty is 10% of the tax not paid by the original return due date.
Can there be a late filing penalty if no tax is due?
Yes. If no tax is due, the Commissioner of Revenue Services may impose a $50 penalty for filing a required return or report late.