CT-1065/CT-1120SI Supplemental Attachment: CT-1065/CT-1120SI Supplemental Attachment (Revision 2025-12)
Connecticut · Connecticut DRS · Used for tax years 2025
The 2025 Connecticut Form CT-1065/CT-1120SI Supplemental Attachment provides additional space to report pass-through entity member information, composite return amounts, and members’ shares of Connecticut modifications. It also includes a schedule for parent pass-through entities
Who files this form
The form states that only a parent pass-through entity (PE) must complete Part 1, Schedule D, Connecticut-Sourced Income From Subsidiary PE(s). It does not state a general requirement for who must submit the supplemental attachment.
What you'll need
Have these forms and details available for the parts you complete:
- Federal Schedule K-1 and Schedule CT K-1 for the amounts reported in Part 1, Schedule D.
- Federal Schedule K-1 of Form 1065 or Form 1120S for the Connecticut-sourced items in Part 6.
- Schedule CT K-1, Part 5, Line 6, Column C, for the members’ credit in Part 1, Schedule B.
- Form CT-PET, Part 1, Schedule D, Column I, for the PE tax credit in Part 8, Column B.
- The entity’s Connecticut Tax Registration Number and each member’s number, name, address, FEIN or SSN, member type code, distributive share percentage, and capital ownership percentage.
- Each subsidiary PE’s name and FEIN for Part 1, Schedule D.
Attach statements for other income or loss reported on Part 6, Line 11, and other deductions reported on Part 6, Line 13.
Common mistakes
- Using the wrong year’s form. The form warns that submitting the correct year’s form is required to prevent processing delays. This attachment is for tax year 2025.
- Entering percentages instead of decimals in Part 4. Enter both distributive share and capital ownership percentages as decimals.
- Using negative numbers for Part 5 subtractions. The form says to enter all additions and subtractions as positive numbers.
- Leaving Connecticut modifications out of Part 6. Include the member’s share of modifications from Part 5.
- Exceeding the PET credit limit in Schedule B. Column G cannot exceed the Connecticut income tax liability in Column F.
- Ignoring Schedule D limitations. Amounts in Column B are subject to passive activity, at-risk, and capital loss limitations.
Questions people ask
How is Connecticut income tax liability calculated in Part 1, Schedule B?
Multiply Connecticut-sourced income in Column C by 6.99% (0.0699) to get Column D. Subtract the members’ credit in Column E from Column D to get the liability in Column F.
Where do I enter the supplemental attachment totals on the main return?
Enter the totals from all supplemental attachments on Form CT-1065/CT-1120SI as follows:
- Schedule B: totals for Columns C, D, E, and F go to Part 1, Schedule B, Line 9.
- Schedule D: totals for Columns A, B, C, and D go to Part 1, Schedule D, Line 6.
- Part 8: totals for Columns B, C, D, and E go to Part 8, Line 10.
How do I calculate the total PE tax credit in Part 8?
Add Column B, the PE tax credit from Form CT-PET, to Column C, the indirect credit from Part 1, Schedule D, Column D. Enter the result in Column D. Column E takes amounts from Column D for member type codes NI, NT, NE, and PE only.
Where can I find more information from DRS?
The form directs readers to portal.ct.gov/DRS.