Illinois income tax goes up to 4.95% at the top bracket. Calculate your combined federal + state effective tax rate for 2026. Formula shown, sources cited — no account required.
One of only a handful of states that taxes income at a single flat rate, the state applies 4.95% uniformly to all taxable income regardless of earnings. A minimum-wage worker and a corporate executive pay the same marginal rate. For the median earner at $83,211, state income tax is roughly $4,119 before applying any credits or deductions. This flat structure means there are no bracket cliffs to plan around, but it also means lower-income households pay a similar share of income as high earners, which critics argue is regressive. Federal taxes layer on top at graduated rates, so a middle-income filer here faces a combined effective rate that still differentiates by income. One significant advantage is the retirement income exemption — all pension, Social Security, IRA, and 401(k) income escapes state tax entirely, making this an unusually retirement-friendly tax environment. There is no state alternative minimum tax, and the standard exemption reduces taxable income for most filers. Use the tax bracket calculator to see your state and federal obligations side by side.
Illinois Tax Brackets Explained (2026)
Illinois has a state income tax with a top marginal rate of 4.95%. On top of federal rates (10%–37%), residents can face a combined marginal rate exceeding 35% at higher income levels. However, your effective rate is always lower than the marginal rate because only income above each threshold is taxed at that bracket's rate.
The median household in Illinois earns $83,211/year. At that income (single filer), the federal effective rate is approximately 12–14%, bringing total income tax (federal + state) to roughly 15–17%.
How Marginal vs. Effective Rate Works
The marginal rate is the rate on your last dollar of income — it does not apply to all income. The effective rate is your total tax divided by total income. For example, someone earning $100,000 in Illinois has a 22% federal marginal rate but an effective federal rate of roughly 15%, because the first $44,725 (2024) is taxed at 10% and 12%, not 22%.