CT-1065/CT-1120SI: Connecticut Composite Income Tax Return (2025)
Connecticut · Connecticut DRS · Used for tax years 2025
Form CT-1065/CT-1120SI is Connecticut’s 2025 Composite Income Tax Return for pass-through entities. It reports federal Schedule K information, members’ Connecticut-sourced income and credits, and the composite tax due or overpaid.
What you'll need
Have these records and details available to complete the return:
- Entity information: Name, address, FEIN, Connecticut Tax Registration Number, income-year dates, and dates the business began overall and in Connecticut.
- Federal tax information: Federal Form 1065 or Form 1120S, including the six-digit Business Code Number and Schedule K amounts.
- Member information: Names, addresses, FEINs or SSNs, member type codes, capital ownership percentages, distributive share percentages, and counts of resident and nonresident noncorporate members.
- Income and credit information: Federal Schedule K-1 and Schedule CT K-1 information, Connecticut modifications, and applicable PE tax credit amounts from Form CT-PET.
- Payment records: Payments made with Form CT-1065/CT-1120SI EXT and, for amended returns, prior tax payments and overpayments.
Attach statements for other income or losses and other deductions reported in Part 1, Schedule C, and Part 6. Use supplemental attachments where needed.
If Item F is Yes and either Item G or H is Yes, provide a list of all Connecticut real property owned. For a Yes answer to Item G or H, also provide the requested transfer details.
Common mistakes
- Using the wrong year's form: The form warns that submitting the correct year's form prevents processing delays. Use the 2025 form for tax year 2025.
- Assuming the optional PE tax election can be changed: The form states that this election cannot be amended or revoked.
- Including excluded receipts in Part 2: Do not include receipts from sales or dispositions of tangible personal property or intangible property not held for sale in the ordinary course of business. Also exclude receipts from the sale, rental, lease, or license of real property.
- Including penalty and interest in amended-return payments: Part 1, Schedule A, Line 5e specifically excludes penalty and interest.
- Forgetting your records: Keep a copy of the return.
Questions people ask
What should I complete first?
Complete the Pass-Through Entity Information section first, then Part 1, Schedule C. The form says all PEs must complete Schedule C.
What if the business operates only in Connecticut?
In Part 2, enter 1.000000 (100%) on Line 8 and leave the other lines blank. Complete Part 3 only if the PE carries on business both within and outside Connecticut.
Can I receive a refund by direct deposit?
Yes. The form recommends direct deposit for a faster refund. Complete Lines 8a, 8b, and 8c with the account type, routing number, and account number. Line 8d asks whether the refund will go to a bank account outside the U.S.
Who signs the return?
The form provides a signature line for a general partner or corporate officer, along with fields for the date, title, telephone number, and email address.