Overview

Illinois uses a flat 4.95% tax rate on all taxable income. Understanding how Illinois’s tax system works helps you accurately predict your paycheck and plan your finances throughout the year.

2025 Tax Rates

Illinois taxes all taxable income at a flat rate of 4.95%. This applies equally to all income levels — a $30,000 earner and a $300,000 earner pay the same percentage of their taxable income.

Standard Deduction

Illinois provides a state standard deduction of $0 for single filers and $0 for married filing jointly. This amount is subtracted from gross income before your state tax rate is applied, lowering your overall state tax burden.

Who Must File in Illinois?

Generally, any resident of Illinois who earns income above the filing threshold must file a state income tax return. The Illinois Department of Revenue sets annual filing thresholds, which roughly correspond to the standard deduction amounts.

How Illinois Tax Affects Your Paycheck

Your employer withholds Illinois state income tax from each paycheck based on your W-4 equivalent form and expected annual income. On a $75,000 annual salary, a single filer in Illinois can expect to pay approximately $3,156–$3,713 in state income taxes annually.

Tips to Reduce Your Illinois State Tax Bill

  • Contribute to a pre-tax 401(k) — reduces both your federal and state taxable income
  • Maximize HSA and FSA contributions if available through your employer
  • Claim all applicable deductions — Illinois may allow deductions beyond the standard deduction
  • Review your withholding each year to avoid underpayment penalties

Filing Deadlines

Illinois’s state income tax return is generally due on April 15, aligning with the federal deadline. An automatic extension to October 15 is usually available, but any tax owed must still be paid by April 15 to avoid penalties.

How Illinois Compares to Neighboring States

Illinois borders Wisconsin, Iowa, Missouri, and others. Compared to its neighbors, Illinois’s flat 4.95% rate places it among the lower-tax states in the region.

Use Our Calculator

Want to see your exact Illinois take-home pay? Use our free US Paycheck Calculator — select Illinois from the state dropdown and enter your salary, filing status, and dependents for a complete tax breakdown.

Tax rates based on 2025 data. Laws change frequently — verify with the Illinois Department of Revenue or a tax professional.