A Guide To The Illinois State Income Tax
The state put the question of switching over to a progressive tax system to voters on the November 2020 ballot. But the measure was defeated, and the flat tax remains. How To Calculate Your Illinois Income Tax The starting point for your Illinois tax return is your federal adjusted gross income (AGI). You’ll find your AGI on line 11 of your Form 1040. Your AGI represents your income after adjustments are made to it....