Income Tax for Illinois (2026)
Illinois (IL) Key Facts
Top Marginal Rate
4.95%
Tax Structure
Flat rate
Filing Deadline
April 15
Has State Income Tax
Yes
Number of Brackets
1
How This Calculator Works in Illinois
This calculator applies Illinois's 2026 tax brackets and rates to estimate your state income tax liability. Enter your income and filing status to see your marginal rate, effective rate, and estimated tax owed.
Illinois Overview
Illinois imposes a flat income tax rate of 4.95% on all taxable income, a structure mandated by the state constitution. A 2020 ballot measure to switch to graduated rates was rejected by voters. Notably, Illinois fully exempts all retirement income from state tax — Social Security, pensions, and retirement account withdrawals — making it one of the most retirement-friendly income-tax states in the Midwest.
How Illinois Compares
Illinois's top income tax rate of 4.95% compares to Indiana at 3.05% and Wisconsin at 7.65%. The rate differences can meaningfully impact take-home pay for workers near state borders.
| State | Top Rate | Notes |
|---|---|---|
| Indiana | 3.05% | Indiana has an income tax rate of 3.05%. |
| Wisconsin | 7.65% | Wisconsin has an income tax rate of 7.65%. |
| Missouri | 4.8% | Missouri has an income tax rate of 4.8%. |
Illinois's income tax rate of 4.95% compares to a national average of approximately 5.04%. This is below the national average.
Tips for Illinois Residents
- 1Illinois has a constitutionally mandated flat income tax rate of 4.95% — all taxable income is taxed at the same rate regardless of how much you earn.
- 2In 2020, Illinois voters rejected a proposed constitutional amendment to switch to a graduated income tax, so the flat rate remains in effect.
- 3Illinois does not tax retirement income: Social Security, pensions, 401(k) distributions, and IRA withdrawals are all exempt from state tax.
- 4The state does not allow a standard deduction or personal exemption on the state return — instead, it provides a flat $2,425 personal exemption per person.
- 5Some Illinois municipalities (like Chicago) impose additional taxes through separate mechanisms, though there is no local income tax. Chicago's amusement tax and other city-specific levies add to the overall tax burden.