Illinois Income Tax Structure for 2026
Illinois taxes personal income on a flat schedule. A single flat rate of 4.95% applies to all taxable income above the standard deduction. The standard deduction is $0 for single filers and $0 for married couples filing jointly. A personal exemption of $2,425 (single) or $4,850 (married) further reduces taxable income.
Federal vs. Illinois State Tax: Stacking the Layers
Federal income tax operates on seven brackets ranging from 10% to 37% (2026). On a $75,000 taxable income for a single filer, you'd pay roughly $11,500 in federal income tax after the $14,600 standard deduction. Add Social Security (6.2% × wages up to $176,100) and Medicare (1.45% × all wages) for FICA totaling $5,738 on that same income.
Illinois state tax stacks on top. At $75,000 of taxable wages, Illinois's flat schedule typically adds $2,413—$3,156 of state income tax depending on your specific bracket placement and any state-specific deductions. Total combined burden: roughly 25.0% effective rate on this income level.
Illinois Tax Filing Essentials
Federal returns are due April 15 each year (or the next business day if April 15 falls on a weekend or holiday). Illinois's state return typically follows the same deadline; the Illinois Department of Revenue accepts electronic filing through MeF (Modernized e-File) and most major tax software providers. Extensions push the filing deadline by six months but do not extend the time to pay.
Illinois requires withholding records (W-2 or 1099) and any state-specific deduction documentation (property tax bills, charitable giving receipts, education expense records). Keep records for at least three years (six if you've under-reported income by more than 25%, indefinitely if you've filed a fraudulent return or never filed). Direct deposit refunds typically arrive in 21 days for federal e-filed returns.
Illinois Tax Planning Levers
Pre-tax retirement contributions are the highest-yield tax move for most Illinois earners: a maxed traditional 401(k) ($24,500 in 2026, plus $8,000 catch-up if 50+) reduces both federal and Illinois state taxable income. HSA contributions ($4,400 self-only or $8,750 family in 2026) offer triple tax advantage when paired with a high-deductible health plan.
Cost of living in Illinois sits under the US baseline at 96 (100 = national average). Combined with Illinois's state tax structure, your purchasing power and effective tax rate together determine the real value of a salary here. Use the calculator above to model your specific scenario, then revisit annually as brackets and deductions adjust for inflation.