Bonus Tax Calculator — Illinois (2026)
Bonuses in Illinois are taxed as supplemental wages: the employer usually withholds a flat 22% federal, plus 7.65% FICA and Illinois state withholding. Withholding is not the final tax; the true cost is settled on your return. Enter your bonus to see both. Illinois uses a flat personal income tax of 4.95% applied to taxable income after a state standard deduction of $0.
Illinois Bonus Tax Calculator
The gross bonus before withholding.
Percentage method vs aggregate method
Under the percentage method the bonus is separated from regular pay and hit with the flat 22% federal rate (37% above $1 million of supplemental wages in a year). Under the aggregate method the employer combines the bonus with your normal check and withholds at your marginal rate — which can temporarily withhold far more than 22%.
Either way the bonus is ordinary income. If your marginal federal bracket is 24% or higher, the 22% flat withholding leaves you short at filing time; if you are in the 12% bracket, you are over-withheld and get it back as a refund.
The Illinois layer on bonuses
Illinois taxes bonus income at the same flat rate as salary — up to 4.95%. A $10,000 bonus therefore carries roughly $495 of Illinois tax at the top rate, on top of federal and FICA.
Illinois has no separate city or county income tax, so the state figure above is the full sub-federal income tax you pay.
Reducing the tax on a Chicago bonus
Deferring part of the bonus into a 401(k) or HSA cuts federal and Illinois income tax immediately, though FICA still applies. Some employers allow a separate bonus deferral election — ask payroll before the payment date, not after.
Timing matters too: pushing a bonus into January shifts the tax year, useful if this year included unusually high income from finance work or an equity event.
Local and payroll taxes Illinois adds on top
Illinois adds no state-mandated employee payroll deduction beyond FICA, so nothing extra is taken from your gross pay at the state level.
Illinois has no separate city or county income tax, so the state figure above is the full sub-federal income tax you pay.
Bonuses are wages, so every local layer that applies to your regular Illinois paycheck applies to the bonus too — which is why a supplemental payment often nets a smaller share than your salary does.
Working across a state line from Illinois
Illinois holds income-tax reciprocity agreements with Iowa, Kentucky, Michigan and Wisconsin. If you commute between them, your wages are taxed only by your state of residence — file the exemption certificate with your employer so the wrong state is not withheld from every paycheck.
Remote and hybrid work complicates this further: most states tax income where the work is physically performed, so a Chicago resident spending part of the year at a client site in Indiana may owe a nonresident return there. Keep a day-count log if you split time between states.
The rest of your Illinois tax bill
Illinois charges a 6.25% state sales tax, homeowners pay an average effective property tax of 2.07% of market value, and the minimum wage in force during 2026 is $15.00 an hour.
Chicago's combined rate reaches 10.25%, among the highest in the country.
Income tax is only one part of a state's take. Illinois recovers revenue through sales and property tax as well, which is why headline income tax rates alone are a poor guide to how far a salary really goes. Illinois does not tax retirement income at all — Social Security, pensions, 401(k) and IRA withdrawals are exempt from the flat tax.
Illinois vs Indiana on the same salary
On a $75,000 salary, a single filer keeps about $57,880 a year in Illinois against roughly $59,343 in Indiana — a difference of $1,463, or $122 a month.
Effective combined rates are 22.8% in Illinois and 20.9% in Indiana. Set that gap against living costs: index 93 here versus 90 there, with property tax at 2.07% and 0.84% respectively.
Illinois income tax brackets 2026 (single filer)
| Taxable income | Rate |
|---|---|
| $0 and up | 4.95% |