Form IL-1040-X (2023): Amended Individual Income Tax Return

The IL 1040X, also known as the Illinois Amended Individual Income Tax Return, allows taxpayers to correct errors or omissions made on their original 2023 Illinois individual income tax return (IL 1040).

Who Should File Form IL-1040-X?

  • You made an error on your original IL 1040, such as miscalculating income, deductions, or credits.
  • You received additional income or deductions after filing your original return.
  • The IRS amended your federal return (Form 1040X) and it affects your Illinois taxes.
  • You believe you qualify for a credit or deduction you didn't claim on your original return.

What You'll Need:

  • A copy of your original 2023 IL 1040, including all schedules and attachments.
  • Documentation to support any changes you are making.
  • Form IL 1040X- attached below.

How to file Form IL-1040-X?

  • Complete Form IL 1040X following the instructions provided.
  • Attach all necessary documentation to support your changes.
  • Mail the completed form and documentation to the address listed on the form.

Key Points To Remember About Form IL-1040-X:

  • There is no electronic filing option for Form IL 1040X.
  • Generally, you have three years from the original due date of your return (including extensions) to file an amended return.

To access the current year's Form IL-1040-X, click here.