Illinois charges 4.95% flat state income tax. Use the overtime tax calculator pre-loaded with Illinois rates.
Open Overtime Tax Calculator →When you work overtime in Illinois, each extra hour is subject to federal supplemental withholding (typically 22%), FICA (7.65%), and Illinois's flat 4.95% state tax. Without local income taxes, the state rate is the only additional layer. The overtime calculator shows you the real after-tax value of overtime work with Illinois rates, so you can decide whether extra hours are worth it.
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 overtime tax calculator 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.