Illinois Form IL-1040 — Individual Income Tax Return
How to fill out Illinois Form IL-1040 line by line — who must file, the 4.95% flat rate, exemptions, subtractions for retirement income, credits, and the April 15 deadline.
Illinois
Illinois has a flat 4.95% individual income tax that starts from your federal adjusted gross income, with subtractions for Social Security and most retirement income and a set of nonrefundable credits. It also taxes private-party vehicle purchases through a separate use tax return. The guides below cover each form line by line, with the current figures taken from the official form and instructions.
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