Illinois Income Tax Calculator
Estimate your Illinois state income tax liability. Illinois uses a flat income tax rate of 4.95 percent on all taxable net income, with personal exemptions reducing the base before the rate applies. Enter your filing status and net income and the calculator returns your estimated Illinois tax, effective rate, and the exemption amount applied. Built by The Reed Corporation for clients with Illinois-source income or residency.
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Illinois tax inputs
How Illinois income tax works
Illinois imposes a flat 4.95 percent individual income tax rate on net income. Unlike progressive states with brackets, every dollar of Illinois taxable income is taxed at the same rate regardless of total income. The flat structure makes the calculation straightforward: taxable net income × 0.0495 = Illinois tax due.
Illinois taxable net income starts with federal adjusted gross income, then adds back certain items Illinois doesn’t recognize (such as bonus depreciation differences) and subtracts items Illinois allows but the federal return doesn’t (such as the retirement income subtraction for qualifying pension and Social Security income). The personal exemption further reduces the base before the 4.95 percent rate applies.
Illinois is one of a small number of states with a true flat tax. The personal exemption is $2,425 for single filers, $4,850 for married filing jointly, and $2,425 for each dependent. These amounts are set by the Illinois Department of Revenue and may adjust periodically.
What Illinois doesn’t tax
Illinois does not tax Social Security benefits, most retirement income from qualified plans (401k, IRA, pension distributions if from a qualifying retirement plan), and military pay. This makes Illinois relatively favorable for retirees compared to states that fully tax retirement income. However, Illinois does tax interest, dividends, and capital gains at the full 4.95 percent rate — the same as wage income.
Illinois also imposes a personal property replacement tax on partnerships, S corporations, and trusts at rates of 1.5 percent and 2 percent respectively on net income, separate from the individual income tax. This calculator covers the individual income tax only.