Illinois Income Tax Calculator 2026
Illinois taxes income at a single flat 4.95% rate for 2026 — estimate yours below.
Illinois's flat 4.95% income tax, explained
Illinois (IL) taxes income at a single flat 4.95% rate rather than graduated brackets, so — unlike the federal system — every dollar of Illinois taxable income is taxed at the same rate. That makes the state calculation simple, but it is separate from federal income tax and from Illinois sales tax.
What to know about Illinois tax
- Illinois’ constitution requires a single flat income-tax rate; a 2020 ballot measure to allow graduated rates was rejected.
- Retirement income — including pensions, 401(k) and IRA distributions, and Social Security — is generally exempt from Illinois income tax.
- Combined state-plus-local sales tax is high, especially in the Chicago area, despite the moderate 6.25% state base.
Frequently Asked Questions
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Calculate →Disclaimer
This calculator provides estimates for informational and educational purposes only. SmartTaxCalcs does not provide tax advice. Your actual tax liability may differ based on your specific situation, recent law changes, and circumstances not modeled here (e.g., AMT, NIIT, special credits). We strongly recommend consulting a qualified tax professional (CPA, Enrolled Agent, or tax attorney) before filing or making financial decisions.
Data source: IRS Revenue Procedure / state Departments of Revenue. Last data update: May 19, 2026.