CT-6251: Connecticut Alternative Minimum Tax Return (2024)
Connecticut · Connecticut DRS · Used for tax years 2024
Form CT-6251 calculates Connecticut alternative minimum tax for individuals for 2024. It reports adjustments to federal alternative minimum taxable income, calculates the Connecticut tax, and accounts for any credit for alternative minimum tax paid to qualifying jurisdictions.
Who files this form
For tax year 2024, you must file Form CT-6251 if either applies:
- You were a Connecticut resident or part-year resident and had a federal alternative minimum tax liability.
- You were a Connecticut nonresident, had a federal alternative minimum tax liability, and had Connecticut-sourced income.
If you meet either condition, you must file even if your Connecticut alternative minimum tax is zero.
Taxpayers who do not have a federal alternative minimum tax liability are not required to complete this form.
What you'll need
Have these forms and details available:
- Your federal Form 6251, including Part III if you completed it.
- Your Connecticut Form CT-1040 or Form CT-1040NR/PY, including Schedule 1.
- Your name and Social Security Number as shown on your Connecticut return. For a joint return, include your spouse’s name and Social Security Number.
- If applicable, federal Form 2555 and the federal Form 6251 Foreign Earned Income Tax Worksheet. The Connecticut instructions include a separate Foreign Earned Income Tax Worksheet to complete when required and keep for your records.
- If claiming a credit on Schedule A, copies of the alternative minimum tax returns filed with each qualifying jurisdiction. These must be attached to Form CT-6251.
How to file
- Complete Form CT-6251 in blue or black ink.
- Attach it directly behind Form CT-1040 or Form CT-1040NR/PY. Do not use staples.
- Enter the amount from Form CT-6251, Line 23, on Form CT-1040, Line 9, or Form CT-1040NR/PY, Line 13.
- If claiming the Schedule A credit, attach copies of the alternative minimum tax returns filed with qualifying jurisdictions directly after Form CT-6251.
- If you need more than two Schedule A columns, create a worksheet identical to Schedule A and attach it to the back of Form CT-6251.
The supplied text does not give a mailing address or e-filing directions.
Common mistakes
- Using the wrong year’s form. The instructions warn that you must submit the correct year’s form to prevent processing delays.
- Using a different filing status. Your Form CT-6251 filing status must match your Connecticut income tax return.
- Leaving out required credit attachments. Your Schedule A credit will be disallowed if you do not attach a copy of the return filed with the qualifying jurisdiction.
- Stapling the form or using other ink colors. Do not use staples, and complete the form in blue or black ink only.
- Overlooking the special exemption instructions for younger taxpayers. If you were under age 24 at the end of 2024, follow the federal Form 6251, Line 5, instructions to calculate the exemption amount.
Questions people ask
Do part-year residents and nonresidents calculate the tax differently?
They first calculate Connecticut minimum tax as if they were Connecticut residents, then apportion it. Residents enter 1.0000 on Line 18; part-year residents and nonresidents follow the Line 18 instructions to calculate their apportionment factor.
Do I need to complete Part 2?
Complete Part 2 if you completed Part III of federal Form 6251. However, if Lines 2 and 4 of Form CT-6251 are both zero, skip Part 2 and enter federal Form 6251, Line 7, on Line 12. Special worksheet instructions apply to certain filers who used federal Form 2555.
Can I claim credit for alternative minimum tax paid elsewhere?
Connecticut residents and part-year residents may claim a Schedule A credit for qualifying alternative minimum taxes on income taxed by both Connecticut and a qualifying jurisdiction. Qualifying jurisdictions include another U.S. state, a local government within another state, or the District of Columbia. For part-year residents, the credit applies to qualifying items during the Connecticut residency period. The credit cannot exceed the tax otherwise due.
What if we file jointly federally but separately in Connecticut?
The instructions require you to recalculate your federal alternative minimum tax liability as if your federal filing status were single, using the federal income-allocation rules. If that recalculation produces a federal alternative minimum tax liability, you must calculate Form CT-6251 as a single individual.