CT-1120: Corporation Business Tax Return (2024)
Connecticut · Connecticut DRS · Used for tax years 2024
Form CT-1120 is Connecticut’s 2024 Corporation Business Tax Return. It reports corporate net income, calculates tax on net income and minimum tax on capital, and accounts for credits and payments to determine the balance due or overpayment.
What you'll need
Have these documents and details ready:
- A complete copy of federal Form 1120, including all schedules as filed with the IRS. Attach it to the return.
- The corporation’s FEIN, Connecticut Tax Registration Number, address, total assets, and income-year beginning and ending dates.
- A schedule listing corporate officers’ names, titles, and addresses.
- Records of extension payments, estimated tax payments, and any prior-year overpayment.
Additional attachments depend on your answers and entries:
- Attach schedules for surplus reserves and holdings of stock of private corporations reported in Schedule E.
- Attach Form CT-1120I if the corporation used the annualized method to calculate estimated tax installments.
- Attach Form CT-1120AB if the corporation pays, accrues, or incurs the related-member expenses described in question 10 on page 4.
- If claiming exemption from Connecticut Corporation Business Tax, attach an explanation including the statutory citation.
- For an amendment involving IRS adjustments or federal Form 1120X, attach the IRS notification or federal Form 1120X, as applicable.
- If either Schedule G question 2(a) or 2(b) is answered Yes, attach a list of addresses for all Connecticut real property transferred.
- If IRS audit adjustments were not reported to Connecticut, attach an explanation.
How to file
File Form CT-1120 electronically. Do not mail a paper return to the Department of Revenue Services (DRS). The form directs filers to portal.ct.gov/DRS for more information.
Complete Schedules A, B, and D on page 2 and Schedules E and G on page 3 before completing Schedule C.
Attach the required federal return and supporting schedules. Complete the corporate officer’s signature and date fields, and keep a copy of the return for your records.
Common mistakes
- Mailing a paper return: The form requires electronic filing and says not to mail it to DRS.
- Using the wrong year’s form: The form warns that submitting the correct year’s form helps prevent processing delays. This version is for tax year 2024.
- Completing Schedule C too soon: Complete Schedules A, B, D, E, and G first.
- Missing the federal return attachment: Attach a complete copy of federal Form 1120, including all schedules filed with the IRS.
- Exceeding stated limits: Schedule C, Line 5a must not exceed Line 4. Schedule A, Line 4 must not exceed 50% of Line 3.
- Including penalty and interest in amended-return payments: Schedule C, Line 9d specifically excludes penalty and interest.
- Overlooking the combined-return check: The form asks whether you should file Form CT-1120CU and directs you to the DRS website.
Questions people ask
Can I receive my refund by direct deposit?
Yes. The form recommends direct deposit for a faster refund. Complete Lines 12c, 12d, and 12e with your account type, routing number, and account number. It also asks whether the refund will go to a bank account outside the U.S. and requests the bank name.
Can I apply an overpayment to next year’s estimated tax?
Yes. Schedule C, Line 12a provides a place to enter the amount to be credited to 2025 estimated tax. Enter the amount to be refunded on Line 12b.
How is the starting tax amount determined?
Schedule C, Line 1a uses the greatest of Schedule A, Line 6; Schedule B, Line 6; or $250. Schedule C then includes lines for surtax, credit recapture, credits, and payments.
Do credit refund requests require separate forms?
The form says to file Form CT-RSLP separately when requesting a refund for the Student Loan Payment tax credit. It also says to file Form CT-1120 XCH separately when exchanging R & D tax credits.