IL-1040-X: Amended Individual Income Tax Return (2025)
Illinois · Illinois DOR · Used for tax years 2025
Form IL-1040-X is the 2025 Illinois Amended Individual Income Tax Return. It reports corrected income, exemptions, taxes, credits, and payments to calculate an adjusted refund or amount owed.
Who files this form
Form IL-1040-X is used to amend an Illinois individual income tax return. This version is for tax year 2025.
The form lists federal changes, an accepted net operating loss (NOL), and state changes as reasons for amending. It includes entries for residents, nonresidents, and part-year residents. Nonresidents and part-year residents must attach Schedule NR.
What you'll need
Gather the information and attachments that apply to your changes:
- Personal information: Full Social Security numbers, names, dates of birth, address, and filing status, including spouse information where applicable.
- Federal return information: Form 1040 or 1040-SR for income figures. Attach it if reporting Social Security benefits or qualifying retirement income on Line 5. Attach the federal return and Schedule 1 if reporting an Illinois income tax overpayment on Line 6.
- Amendment records: The filing date of your original IL-1040 or latest IL-1040-X, and a detailed explanation of your changes. Attach a copy of federal Form 1040X or Form 1045 if you filed one. For a federal change or accepted NOL, attach a copy of your federal finalization.
- Income and exemption schedules: Schedule M for other additions or subtractions; Schedule IL-E/EITC for dependents; and Schedule NR for nonresidents or part-year residents.
- Tax and credit schedules: Schedule 4255 for investment tax credit recapture; Schedule CR for income tax paid to another state while an Illinois resident; Schedule ICR for the listed property tax, education expense, and volunteer emergency worker credits; and Schedule 1299-C for its credit.
- Payment and refundable credit records: Schedule IL-WIT for Illinois withholding; Schedule K-1-P or K-1-T for pass-through withholding or the pass-through entity tax credit; and Schedule IL-E/EITC for the Earned Income Tax Credit or Child Tax Credit. The form also provides a place to staple W-2 and 1099 forms.
- Earlier payment and overpayment amounts: Estimated payments, payments made with or after the original return, and the overpayment shown on the original return or adjusted by the Department.
- Refund or payment details: Bank routing and account numbers if choosing direct deposit. If enclosing a check, the form provides a place to staple it with IL-1040-X-V.
How to file
- Enter your personal information and corrected figures. Check the box in Step 1 if your Social Security number, name, or address differs from your previously filed return.
- Complete the tax, payment, and adjusted refund or amount-owed calculations. Attach the schedules that apply.
- In Step 11, identify why you are amending, enter the requested filing and acceptance dates, and explain the changes in detail. Attach a separate explanation sheet if needed.
- Sign and date the return. For a joint return, both spouses must sign.
- If enclosing payment, staple your check and IL-1040-X-V in the marked place. Staple W-2 and 1099 forms in their marked place.
The form directs you to the 2025 IL-1040-X Instructions for required attachments and the mailing address. Those instructions were not provided here, so no mailing address or e-filing directions are available in the supplied text.
Common mistakes
- Filing before IRS acceptance: If a change to your federal return resulted in an overpayment and you are changing your Illinois return because of it, do not file IL-1040-X until you receive notice that the IRS accepted the changes.
- Using partial Social Security numbers: Provide the entire number for each person whose SSN is required.
- Changing use tax: Line 21 must stay the same as the use tax reported on your original return.
- Including interest on Line 35: Do not include interest you received in the prior overpayment amount.
- Exceeding calculation limits: Line 14 cannot be less than zero, and total credits on Line 18 cannot exceed the tax on Line 14.
- Missing a spouse’s signature: Both spouses must sign a joint return.
- Skipping exemption instructions: The form says to read the instructions before completing Step 4.
Questions people ask
Can I receive my refund by direct deposit?
Yes. On Line 37, choose direct deposit and provide your routing number, account number, and whether the account is checking or savings. You may choose a paper check instead.
Can I apply some of my overpayment to estimated tax?
Yes. Line 38 applies the difference between your Line 36 overpayment and the refund you request on Line 37 to estimated tax.
Do I need to attach my federal amended return?
If you filed federal Form 1040X or Form 1045, Step 11 requires you to attach a copy. The form also calls for a copy of your federal finalization for a federal change or accepted NOL.
How should I explain my changes?
Use Step 11, Part D to explain your reasons for amending in detail. Attach a separate sheet if you need more space.
Can someone else discuss this return with the Department?
Yes. The signature section has a box allowing the Department to discuss the return with the third-party designee you identify there.