Mail in your Illinois state tax return is Form IL-1040 and all necessary supporting schedules, form, and attachments. There is a link below so you can see a blank Illinois state form. Don't forget to sign and date your tax forms before you mail them.
Attach all necessary W-2 and 1099 forms to your Form IL-1040:
- If you are claiming Illinois Income Tax withheld on Line 26, 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 of your Schedule NR.
- If you are annualizing your income, you must complete and attach Form IL-2210.
http://www.revenue.state.il.us/Individuals/AvoidCommonFilingMistakes.htm
http://www.revenue.state.il.us/taxforms/incmcurrentyear/individual/il-1040.pdf