How to Use This Calculator
Enter your income, filing status, and any deductions. The calculator computes your Illinois state income tax alongside your federal tax, showing exactly how much goes to each and what you take home.
The most useful thing to try? See how Illinois's flat 4.95% rate affects different income levels, then test how deductions and retirement contributions change your bottom line.
Here's what each field means:
Annual Income is your total earnings before any taxes. Include wages, freelance income, investment income, and any other sources.
Filing Status determines which deductions and exemptions apply. Illinois uses filing statuses similar to the federal system.
Illinois Income Tax: What You Need to Know
Illinois uses a flat income tax of 4.95% on all taxable income. Unlike states with progressive brackets, everyone pays the same percentage regardless of how much they earn. A teacher making $45,000 and a CEO making $500,000 both pay 4.95%.
Illinois has a constitutionally mandated flat income tax — the state constitution requires that any income tax be applied at a single rate. The current rate is 4.95%. In 2020, voters rejected a constitutional amendment that would have allowed a graduated tax system. Illinois doesn't have a standard deduction; instead, it offers a personal exemption of $2,625 per person. Taxable income starts with your federal AGI (not federal taxable income), so the federal standard deduction doesn't carry over. This means Illinois effectively taxes more of your income than states that conform to the federal standard deduction.
A Real Example
Let's say you're a single filer earning $75,000 in Illinois. Your approximate Illinois state income tax would be around $3,581, for an effective state tax rate of about 4.8%.
That's just the state portion. Federal income tax and FICA taxes are additional.
Deductions and Exemptions
Personal exemption of $2,625 per person. Illinois does not tax retirement income (including pensions, Social Security, 401(k) and IRA distributions). This makes Illinois surprisingly attractive for retirees despite the 4.95% rate on other income. The state also offers a property tax credit and an education expense credit.
Local Taxes
No local income taxes in Illinois (though Cook County and Chicago have various other taxes that affect residents).
Recent Changes
The 4.95% rate has been in effect since 2017. There have been periodic discussions about raising it, but the flat tax structure is constitutionally protected.
How to Use This Calculator Strategically
Model a raise or job change. With a flat tax, the math is simpler — every additional dollar is taxed at 4.95%. But deductions and credits can still shift your effective rate.
Compare filing statuses. Even with a flat rate, different filing statuses unlock different deduction amounts that can affect your bottom line.
Plan retirement contributions. See how 401(k) or IRA contributions reduce your Illinois taxable income and lower your state tax bill.
Evaluate a move. Compare Illinois's flat 4.95% rate to other states. Depending on your income level, a flat tax state might save you money — or cost you more — compared to a progressive system.
References
- Illinois Department of Revenue. (2025). Individual Income Tax.
This calculator is for educational purposes only and does not constitute tax or financial advice. Tax rates and rules change regularly. Consult a qualified tax professional for guidance specific to your situation.