Illinois charges 4.95% flat state income tax. Use the quarterly tax estimator pre-loaded with Illinois rates.
Open Quarterly Tax Estimator →Quarterly estimated payments in Illinois must cover both your federal and state obligations. Illinois applies a flat 4.95% rate, and most states require their own quarterly payment schedule that may differ from the IRS dates. This estimator pre-loads Illinois's tax rates so you can calculate both federal and state quarterly amounts in one place, avoiding underpayment penalties at both levels.
Illinois levies a flat 4.95% state income tax on all taxable income regardless of how much you earn. This makes tax planning straightforward: for every additional dollar you earn, 4.95 cents goes to Illinois. Illinois does not impose local income taxes, so the 4.95% flat rate is the only state-level income tax you owe.
The table below shows what you actually keep at five salary levels in Illinois, accounting for federal tax, FICA, and Illinois's flat 4.95% state tax.
See how Illinois compares to other Midwest states. Each link takes you to the quarterly tax estimator landing page for that state.
For a comprehensive breakdown of Illinois’s tax structure, salary comparisons, cost-of-living analysis, and more, visit the full Illinois take-home pay page.