What is the state income tax rate in Illinois?
Illinois uses a flat state income tax rate of 4.95% for 2026, applied after the Illinois personal exemption ($2,925 single, $5,850 married filing jointly). There is no separate graduated state bracket system like California or New York. Most Illinois employees have no local income tax withheld on wages; your actual withholding can still vary with allowances, bonuses, and uncommon local add-ons not modeled here.