Illinois (IL) Paycheck Calculator

Illinois has a flat individual income tax rate of 4.95%. This rate has been in place since 2017 (it was temporarily increased from 3.75% to fund the state budget). Illinois taxes 'net income,' which for W-2 employees is approximately federal AGI minus the Illinois personal exemption allowance. Source: Illinois Department of Revenue (tax.illinois.gov).

The Illinois personal exemption allowance for 2026 is $2,925 per exemption, up from $2,850 in 2025. The allowance is indexed for inflation using a formula that starts from a base amount of $2,050. For single filers it is $2,925; for married filing jointly it is $5,850 (2 exemptions × $2,925). The exemption is phased out when federal AGI exceeds $250,000 (single) or $500,000 (MFJ). Source: tax.illinois.gov/questionsandanswers/851.html.

Yes. Traditional 401(k) contributions reduce your federal W-2 wages, which reduces your federal AGI. Since Illinois starts from federal AGI (with modifications), 401(k) deferrals also reduce your Illinois net income and therefore your IL income tax. A 6% contribution on an $80,000 salary saves approximately $237 in Illinois income tax ($4,800 × 4.95%).

No. Illinois has a constitutionally mandated flat income tax — all income is taxed at the same 4.95% rate. The Illinois Constitution (Art. IX §3) requires a flat rate for individuals. Proposals to move to a graduated rate structure have failed at ballot. This means every dollar of your W-2 income above the personal exemption is taxed at 4.95%.

This calculator uses the IRS Publication 15-T percentage method (annualized wages, post-2020 W-4). Your annual salary is reduced by any pre-tax deductions you enter, then by the federal standard deduction for your filing status. The resulting federal taxable income is run through the 2026 federal income tax brackets to get the annual withholding, which is divided by your pay periods.

Social Security is 6.2% of your gross wages up to the 2026 wage base of $184,500. Medicare is 1.45% of all wages with no cap. High earners (above $200,000 for single filers, $250,000 for married filing jointly) also owe an Additional Medicare surtax of 0.9% on wages above that threshold. These are the employee shares; your employer pays a matching amount separately.

Yes. Traditional 401(k) contributions reduce your federal taxable income (and therefore your federal income tax withholding). They also reduce the tax base in most states, including Illinois. Roth 401(k) contributions are post-tax and do not reduce current-year tax.

This calculator covers federal income tax, FICA (Social Security + Medicare), and Illinois state income tax. It does not include: Excludes Illinois local taxes and the 1.5% Personal Property Replacement Tax (PPRT) that applies to S-Corps and partnerships at entity level. SDI is not applicable in Illinois. Age-related additional exemption ($1,000 per qualifying condition) is excluded. It is an estimate for budgeting purposes — your employer's actual payroll system and your W-4 elections determine your exact withholding.

Your marginal tax rate is the rate that applies to your last dollar of income (the highest bracket you fall into). Your effective tax rate is your total taxes divided by your gross salary — it is always lower than your marginal rate because lower income is taxed at lower bracket rates. The effective rate shown here includes federal income tax, FICA, and state income tax.