You must
attach all W-2 and 1099 forms that show Illinois Income Tax withheld.
If no payment is enclosed, mail your return to:
ILLINOIS DEPARTMENT OF REVENUE
SPRINGFIELD IL 62719-0001
If a payment is enclosed, mail your return to:
ILLINOIS DEPARTMENT OF REVENUE
SPRINGFIELD IL 62726-0001
For more information:
http://tax.illinois.gov/TaxForms/IncmCurrentYear/Individual/IL-1040-Instr.pdf
