2025 Form CT-1040X
Amended Connecticut Income Tax Return for Individuals
Download or Print 2025 Connecticut Form CT-1040X
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About Connecticut Form CT-1040X
Connecticut Form CT-1040X is used to amend a Connecticut individual income tax return after the original return has been filed. The form may be used to correct a resident, part-year resident, or nonresident return. The Form CT-1040X PDF includes the amended return, Schedules 1 through 4, a withholding schedule, a tax calculation schedule, an explanation section, payment and refund lines, signature fields, and filing instructions.
Use the Form CT-1040 instructions or Form CT-1040NR/PY instructions to review the original return items you are changing. If you are claiming EITC on Form CT-1040X, Connecticut DRS says you must include Schedule CT-EITC with your amended return.
Connecticut Form CT-1040X PDF Files by Year
Click any of the Connecticut Form CT-1040X PDF links above to download, save, view, and print the file for the corresponding year. These free PDF files are unaltered and are sourced directly from the publisher.
Related Connecticut State Income Tax Forms
Need to download more state income tax forms? View the full 2025 Connecticut income tax forms list.
| Form Code | Form Name |
|---|---|
| Form CT-1040 | Connecticut Resident Income Tax Return |
| Form CT-1040NR/PY | Connecticut Nonresident and Part-Year Resident Income Tax Return |
| Form CT-6251 | Connecticut Alternative Minimum Tax Return |
| CT-1040 TCS | Connecticut Tax Calculation Schedule |
Frequently Asked Questions (FAQ)
Here are answers to common questions about downloading, printing, completing, and filing 2025 Connecticut Form CT-1040X.
When should I file 2025 Connecticut Form CT-1040X?
File Form CT-1040X after you determine that a previously filed Connecticut income tax return needs to be corrected. If the amended return shows additional tax due, pay the amount due as soon as possible to limit penalties and interest. Review the instructions if you are filing an amended return to claim a refund or credit.
Do I need to file Form CT-1040X if my federal return changes?
Yes, if the federal change also changes your Connecticut income tax. Connecticut DRS says you must file Form CT-1040X when the IRS or federal courts change or correct your federal income tax return and the change results in Connecticut income tax being overpaid or underpaid. You must also file Form CT-1040X if you filed a timely amended federal income tax return and that amendment changes your Connecticut income tax.
What is Connecticut Form CT-1040X used for?
Use Form CT-1040X to correct a Connecticut individual income tax return that was already filed. Common amended return changes can involve income, deductions, additions, subtractions, credits, tax, payments, refund amounts, or balance due amounts.
Who should use Form CT-1040X?
Use Form CT-1040X if you need to amend a Connecticut income tax return for an individual taxpayer. The form may be used to amend a Connecticut resident, part-year resident, or nonresident return, depending on the return originally filed.
Do I need to attach schedules to Form CT-1040X?
Attach any Connecticut schedules, credit forms, or supporting documents needed to explain the changes on your amended return. If you are claiming EITC on Form CT-1040X, Connecticut DRS says you must include Schedule CT-EITC with your submission.
Is Form CT-1040X the same as Form CT-1040?
No. Form CT-1040 is the Connecticut resident income tax return for an original filing. Form CT-1040X is used later when you need to amend or correct a Connecticut individual income tax return that was already filed.
Last updated: August 1, 2026
References:
- Form CT-1040X Amended Connecticut Income Tax Return for Individuals. State of Connecticut, Connecticut Department of Revenue. Retrieved August 1, 2026.
- Individual Income Tax Forms. State of Connecticut, Connecticut Department of Revenue. Retrieved August 1, 2026.
- Form CT-1040 Connecticut Resident Income Tax Return. State of Connecticut, Connecticut Department of Revenue. Retrieved August 1, 2026.
- Form CT-1040NR/PY Connecticut Nonresident and Part-Year Resident Income Tax Return. State of Connecticut, Connecticut Department of Revenue. Retrieved August 1, 2026.