Illinois Tax Authority
Official Illinois state tax information, forms, and filing resources.
Source: Illinois Department of RevenuewebpageApplies to: 2025
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Illinois Income Tax
Illinois uses a flat income tax rate applied to all taxable income. Combined with federal tax, this determines your total income tax burden.
Income Tax Brackets
The U.S. federal income tax uses seven progressive brackets with rates from 10% to 37%. Each bracket rate only applies to the income within that range — not to your entire income.
Last reviewed: 2027-01-15 • State: IL