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Illinois Income Tax Guide

Flat 4.95% income-tax rateIllinois applies one individual income-tax rate to net income after supported adjustments.
$2,925 personal exemptionThe 2026 allowance is subject to federal-AGI limits and can be unavailable at higher income.
Federal AGI starting pointIllinois generally begins with federal adjusted gross income, then applies state additions and subtractions.
Official SourcesIL tax rate2026 exemptionTaxable incomeIRS
IL tax rate2026 exemptionTaxable incomeIRS
Calculate for Illinois

How Illinois taxes work

Federal adjusted gross income begins the calculationIllinois generally starts with federal AGI and then applies state-specific additions and subtractions to reach base income.
Personal exemptions reduce net incomeThe calculator applies $2,925 once, or twice jointly, unless income exceeds $250,000 for most filers or $500,000 jointly.
The rate is a flat 4.95%The same statutory percentage is applied to the supported Illinois net-income estimate.
Return-specific adjustments remain outsideIllinois additions, subtractions, dependent exemptions, recapture, and state credits can change an actual return.

Common Illinois tax questions

Does filing status change the Illinois rate?No. The rate remains 4.95%, although exemptions and return-specific amounts can differ.
Are dependent exemptions included?No. The estimate includes basic taxpayer and spouse allowances only; dependent exemptions and Illinois credits require separate review.
Are retirement contributions reflected?Common pre-tax contributions reduce the federal AGI-style wage base used by this simplified Illinois estimate.
Are sales and property taxes included?No. Those taxes vary by purchase or location and are outside this income and take-home-pay calculation.
What about part-year or nonresident income?The calculator is primarily a full-year resident estimate and does not perform Illinois income allocation.
Is this the same as Form IL-1040?No. It is a planning estimate, not a filed return or a calculation of every Illinois adjustment and credit.