Illinois uses a flat income tax
Illinois taxes every dollar of taxable income at a single rate of 4.95%, with no brackets to move between.
The flat rate is still the ceiling rather than the going rate. Because Illinois subtracts a deduction or exemption before applying it, $2,300 on $50,000 is an effective 4.66% of gross while $7,300 on $150,000 is 4.85%, closer to the headline 4.95%, but only approaching it as income rises.
Illinois income tax brackets for 2026
Single filer rates. Married couples filing jointly use the same rates and the same thresholds, and on $120,000 a joint return works out at $5,700, the same as two single filers on $60,000 each pay between them.
| Rate | Taxable income over |
|---|---|
| 4.95% | $0 |
Worked examples for Illinois
Using Illinois's 2026 rates, standard deduction and exemptions:
| Situation | Illinois tax | Effective state rate |
|---|---|---|
| Single, $60,000 | $2,825 | 4.71% |
| Single, $120,000 | $5,795 | 4.83% |
| Married filing jointly, $120,000 | $5,650 | 4.71% |
The joint figure is lower than the single figure on the same $120,000 only because the joint return covers two people's exemptions or credits; the rates themselves are the same.
No state standard deduction
Illinois gives no state standard deduction, so only a personal exemption of $2,925 stands before the rates: an $85,000 salary is taxed here on $82,075 of itself, where a state allowing the federal-sized $16,100 would tax $68,900.
Rules specific to Illinois
The provisions published for Illinois:
- As of June 1, 2017, taxpayers cannot claim the personal exemption if their adjusted gross income exceeds $250,000 (single filers) or $500,000 (MFJ).
Provision notes quoted from the Tax Foundation's State Individual Income Tax Rates and Brackets, which is also the source of the rate and bracket data on this page.
Illinois cannot legally have brackets
The Illinois constitution requires that income be taxed at a single non-graduated rate. This is not a policy preference that could be changed by legislation: in November 2020 voters were asked to amend the constitution to permit graduated rates, with the replacement schedule already written into law, and they rejected it. The flat 4.95% above is therefore constitutionally entrenched in a way that Indiana's or Kentucky's is not.
The provision that matters most to residents is the opposite of restrictive. Illinois does not tax retirement income at all: not Social Security, not pensions, not distributions from 401(k)s or IRAs. Among states with an income tax, that is about as generous as retirement treatment gets, and it makes the state far cheaper for a retired household than its rate suggests.
The revenue has to come from somewhere, and in Illinois it comes substantially from property tax, where effective rates are among the highest in the country. A retiree moving in pays little income tax and a great deal on the house.
Working across the Illinois border
Illinois has reciprocity agreements with Iowa, Kentucky, Michigan, Wisconsin. If you live in one of those states and work in Illinois, you pay income tax only to your home state: file an exemption certificate with your employer and no Illinois tax is withheld. See what happens if you skip that certificate.
Retirement income in Illinois
Illinois does not tax Social Security benefits, which puts it with the large majority of states. Pensions and IRA or 401(k) withdrawals are treated separately. See how states treat retirement income.
As an upper bound, $60,000 of retirement income taxed as ordinary wage income would cost about $2,800 here, an effective 4.71%. Any exclusion Illinois grants for pension or retirement-account income comes off that figure, so a retiree's real rate is usually lower than the brackets above suggest.
How Illinois compares
Illinois's top marginal rate of 4.95% ranks 24 of the 42 jurisdictions that tax income (41 states and D.C.). Indiana tops out at 2.95%. Wisconsin tops out at 7.65%. Missouri tops out at 4.7%. Iowa tops out at 3.8%.
Filing and deadlines
Illinois's return is due in mid-April with your federal return. Deadlines and extensions covers the off-cycle states and what an extension does not buy you.
What this estimate covers
The figure applies Illinois's published 2026 rates and deductions to wage income, alongside federal tax and FICA (a well-sourced estimate, not a return). See what these calculators do and do not model.