CT-1120 EXT: Application for Extension of Time to File Corporation Business Tax Return (2024)
Connecticut · Connecticut DRS · Used for tax years 2024
Form CT-1120 EXT requests an extension of time to file a 2024 Connecticut Corporation Business Tax Return, either Form CT-1120 or Form CT-1120CU. It reports tentative tax, credits, payments, and the amount due with the extension request. The extension gives you more time to file,
Who files this form
Corporations seeking more time to file their 2024 Connecticut Corporation Business Tax Return, Form CT-1120 or Form CT-1120CU, use Form CT-1120 EXT.
For a combined unitary group, the Designated Taxable Member should file one extension request for all members included in Form CT-1120CU. Payments should use the Designated Taxable Member’s Connecticut Tax Registration Number.
When it's due
- 2024 calendar-year return: The extension request is due May 15. The form requests an extended filing date of November 15, 2025.
- 2024 fiscal-year return: File the extension request by the fifteenth day of the month following the due date of the corporation’s corresponding federal income tax return. Enter the fiscal year-end date and requested extended filing date on the form.
- If the due date falls on a Saturday, Sunday, or legal holiday, filing on the next business day is considered timely.
The extension gives you more time to file, not more time to pay. Pay the amount shown on Line 15 with the extension request.
What you'll need
Have the following information ready to complete the form:
- Corporation or Designated Taxable Member name, address, Connecticut Tax Registration Number, and federal employer identification number (FEIN).
- Income-year beginning and ending dates.
- Whether federal Form 7004 was filed. If it was not, an explanation of why you need the Connecticut extension.
- Tentative tax, applicable surtax and tax credit recapture, tax credits, estimated tax payments, and any prior-year overpayment.
- The expected Pass-Through Entity tax credit for Line 10, if applicable.
- For combined unitary filers, the number of taxable members and the group’s tax information.
A corporate officer must sign. Someone with a signed Power of Attorney may sign instead. A paid preparer must sign and date the form and provide an SSN or PTIN and the firm’s FEIN.
How to file
File electronically
Electronic filing and payment are required. Use 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-1120 EXT.
Complete the form in full and pay the amount on Line 15. The instructions require an electronic payment when filing through myconneCT. You may pay by direct withdrawal from a checking or savings account, or by credit or debit card. Card payments carry a convenience fee. Save your confirmation number.
Waivers and mailing
To request a waiver from electronic filing, visit portal.ct.gov/DRS and complete Form DRS-EWVR, Electronic Filing and Payment Waiver Request. The form warns not to mail a paper return under the electronic filing requirement.
For paper filing under the waiver process, use blue or black ink and no staples. If you have an electronic payment waiver, make your check payable to Commissioner of Revenue Services. Write “2024 Form CT-1120 EXT” and the corporation’s Connecticut Tax Registration Number on the front. Sign the check and paper clip it to the front of the return. Do not send cash.
Mail a paper return with payment to:
Department of Revenue Services
State of Connecticut
PO Box 2974
Hartford CT 06104-2974
Mail a paper return without payment to:
Department of Revenue Services
State of Connecticut
PO Box 150406
Hartford CT 06115-0406
Common mistakes
- Treating the extension as extra time to pay. It extends only the filing deadline. Late payment is subject to penalty and interest.
- Using the wrong year’s form. The instructions require the correct year’s form to avoid processing delays.
- Sending a check through online banking instead of an electronic funds transfer. Verify that your bank sends an EFT, not a check. Failure to pay electronically can trigger penalties.
- Exceeding the credit limits. Line 8 must not exceed Line 7. The PE credit on Line 10 must not exceed Line 9.
- Skipping paper-payment details when a waiver applies. Sign the check, include the required identifying information, and use a paper clip rather than staples.
- Not keeping a copy. The form reminds you to keep a copy for your records.
Questions people ask
How much extra filing time can I request?
Most corporations may request six months. Corporations with a June 30 fiscal year end may request seven months.
Do I need a federal extension first?
No. If you filed federal Form 7004, you do not need to give a reason for the Connecticut request. If you did not file Form 7004, you may request a Connecticut extension for reasonable cause and must explain your request.
Does a federal extension remove the payment requirement?
No. Each corporation must submit payment of any tax due or believed to be due with the Connecticut extension request, whether or not a federal extension has been approved.
Can I avoid an underpayment penalty if my filing extension is granted?
The instructions say you may avoid the penalty for failing to pay the full amount by the original deadline if you pay at least 90% of the tax shown on the return by that deadline and pay the balance when filing Form CT-1120 or CT-1120CU by the extended deadline. Interest is assessed at 1% per month or fraction of a month on underpaid tax from the return’s due date.