CT-1120CU-MI: Combined Group Member Information (2025)
Connecticut · Connecticut DRS · Used for tax years 2025
Form CT-1120CU-MI provides member information for Connecticut’s Combined Unitary Corporation Business Tax Return, Form CT-1120CU. It reports taxable and nontaxable members’ identifying information, tax status, credits and payments, along with mergers, members that left the group,
Who files this form
Complete and attach Form CT-1120CU-MI as part of Form CT-1120CU, Combined Unitary Corporation Business Tax Return. It provides information about the taxable and nontaxable members included in the combined return.
- A taxable member is subject to Connecticut Corporation Business Tax and has nexus in Connecticut.
- A nontaxable member is not subject to that tax and does not have nexus with Connecticut.
Companies exempt from Corporation Business Tax are not included in the combined unitary return.
What you'll need
Gather the following information to complete the form:
- The designated taxable member’s Connecticut Tax Registration Number.
- Each member’s name, assigned member number, Connecticut Tax Registration Number if applicable, FEIN, and NAICS code for its principal business activity.
- Each member’s taxable status, new-member status, company type, and whether Public Law 86-272 applies.
- Refundable tax credits from Form CT-1120K, Part I-E, Line 5; extension payments from Form CT-1120 EXT; estimated payments from Forms CT-1120 ESA, ESB, ESC, and ESD; and prior-year overpayments being credited to the current period.
- Information about any business reported separately on Form CT-1120 or in another combined group’s Form CT-1120CU.
- Names, FEINs, and relevant dates for mergers and members that left the group, plus reasons for departures.
- Names, FEINs, and reasons for exclusion for commonly owned domestic companies not included in the return.
Previously filed combined returns provide the member numbers needed to keep those assignments consistent.
How to file
Complete Form CT-1120CU-MI and attach it to Form CT-1120CU.
- Part I: Use a separate column for each taxable and nontaxable member. Enter identifying information, answer the status questions, and report credits and payments.
- Part II: Report mergers involving members of the previously filed combined return as described in the instructions.
- Part III: Report members that left the group since the last return, other than mergers with another group member reported in Part II.
- Part IV: List commonly owned domestic U.S. companies excluded from this return and explain why they are excluded.
If filing a paper Form CT-1120CU, the member numbers on Page 2 must match those assigned on Form CT-1120CU-MI. The supplied text does not provide a mailing address or e-filing directions.
Common mistakes
- Changing member numbers: Assign whole-number identifiers beginning with 1 in ascending order. Each identifier stays with its assigned member throughout the combined unitary series of returns.
- Using inconsistent numbers on a paper return: Member numbers on Page 2 of Form CT-1120CU must match Form CT-1120CU-MI.
- Including too much of a member’s business: If only part of its operations belongs in this combined return, include only the income, capital, and apportionment factors related to that portion when calculating the group’s tax.
- Reporting the same merger as a departure: Part III excludes mergers with another combined group member already reported in Part II.
Questions people ask
What if a member does not have a FEIN?
Enter NoFederalID on Line 3 for that member.
What if a nontaxable member has no Connecticut Tax Registration Number?
Leave Line 2 blank for that member.
How are members protected by Public Law 86-272 treated?
Check Yes on Line 9 for a taxable member conducting business in Connecticut whose net income is protected from taxation by Public Law 86-272. These members are treated as nontaxable for net income base purposes, but taxable for all other purposes.
Which companies belong in Part IV?
List domestic U.S. companies that share common ownership with the combined group but are not included in this Form CT-1120CU. Explain why they are excluded.
Which identifier does Line 17 request?
The form label requests the FEIN of the designated taxable member of the different combined group. The included Line 17 instructions instead request that member’s Connecticut Tax Registration Number when Line 16 is Yes. The supplied text does not resolve this difference.