Illinois Department of Revenue

Avoid Common Filing Mistakes for Individual Income Tax


Filing electronically is the best way to avoid common, and sometimes costly, mistakes. You can file your Form IL-1040 for free using MyTax Illinois. Once you submit your return electronically, do not mail a copy. If you choose to make a payment via check, use Form IL-1040-V.

Use the following information to assist you in avoiding processing delays and receiving your refund faster.

Use a calculator. Review the entries you made on each line for accuracy and verify your calculations.

Make sure you use the correct Form IL-1040. This return is tax year specific. For the return due April 15, 2014, you should be using the 2013 Form IL-1040.

Do not send multiple Form IL-1040 returns.

  • If you filed electronically, you may check on the status of your refund within two weeks of receiving acknowledgement that we accepted your return.
  • If you filed a paper return, you may check on the status of your refund within 12 weeks of the date that you submitted your return.
  • If you made an error on your original return and need to file a correction (amendment), do not file another Form IL-1040. Instead, you must complete and submit Form IL-1040-X with any necessary supporting documentation. Do not forget to attach your federal finalization if your change was due to a federal change.

Attach all necessary W-2 and 1099 forms to your Form IL-1040

  • If you are claiming Illinois Income Tax withheld on Line 25, you must attach all W-2 and 1099 forms that show Illinois Income Tax withheld. If your W-2 is incorrect, you must obtain a corrected W-2 from your employer and attach it to your return.
  • If you are filing Schedule CR to claim credit for taxes paid to other states or municipalities, include any W-2 or 1099 that supports your claim of income that is double taxed.

Include all necessary supporting schedules, forms, and attachments with your Form IL-1040

  • If you are claiming property tax credit, education expense credit, or earned income credit (EIC), you must complete and attach Schedule ICR. Do not forget to include your property index number(s) and county name(s) for property tax credit.
  • If you are claiming a subtraction for Social Security or retirement income on Line 5, you must attach U.S. 1040 or U.S. 1040A, Page 1 and any W-2 and 1099 forms related to your subtraction.
  • If you list other additions on Line 3 or other subtractions on Line 7, you must complete and attach Schedule M.
  • If you are a part-year or nonresident of Illinois, you must complete and attach Schedule NR. Unemployment income is taxed by Illinois if you earned it while an Illinois resident or you received it from the Illinois Department of Employment Security (IDES). This income should be included on Line 17.
  • If you are in a civil union, you must file your Illinois return with your civil union partner and complete and attach Schedule CU.
  • If you are annualizing your income, you must complete and attach Form IL-2210.

Double check all personal information in Step 1 of Form IL-1040

  • Verify that your Social Security number (SSN), name, and address are correct. If you are married, you must include your spouse’s SSN and name, even if you are filing separately.
  • You must check ONE box for filing status – do not leave Line C blank.
  • Clearly print all information.

Complete all lines of Form IL-1040

  • Form IL-1040 is a two-page form. Make sure you complete both sides. Fill out all lines that apply. Pay attention – Line 23 requires an entry, even if you are not paying use tax on Form IL-1040 (put zero if that is true).
  • You must sign your return. If you are filing a joint return, both you and your spouse must sign the return.

Verify certain amounts on our website

Important reminders if you are receiving a refund

  • If you enter an amount on Line 36, you must check one box on Line 37 to indicate how you would like us to issue your refund.
  • Direct deposit is the fastest way to receive your refund. Do not forget to include your routing and account numbers. If you do not know them, contact your financial institution to verify.

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