Illinois Capital Gains Tax 2026: Flat 4.95% state rate

Illinois capital gains tax planning starts with the federal rules, then layers on Illinois's own treatment (flat 4.95% state rate). This calculator estimates both so you can see a combined effective rate before you sell stocks, crypto, real estate, or other capital assets.

Federally, short-term gains (held one year or less) are taxed as ordinary income, while long-term gains generally use 0%, 15%, or 20% preferential rates for tax years 2025 and 2026. High earners may also owe the 3.8% Net Investment Income Tax when MAGI exceeds the IRS threshold for their filing status.

Illinois applies a flat state rate to capital gains in our model (Flat 4.95% state rate). Flat-rate states are simpler to estimate than graduated systems, but deductions, credits, and local rules can still change your final bill — always confirm with the official revenue agency.

Illinois figures in this model are drawn from the official source we cite for the state: https://tax.illinois.gov/. Confirm the current-year statute or agency page before you file — rates and special rules can change.

Illinois is encoded as a flat 4.95% state rate on taxable capital gain. Holding period does not change that 4.95% in this model.

A flat rate makes the state line easier to read than a graduated table: taxable gain times 4.95%. Deductions and retirement subtractions that Illinois allows on a real return are not computed here.

Rates last verified: August 2026. Official source: https://tax.illinois.gov/.

Use the calculator above with filing status and income to stack federal long-term or short-term tax, NIIT, and Illinois state tax. Compare nearby states from the links below, review our methodology for data sources (including Illinois's official reference), and consult a CPA before filing. This page is educational and not tax advice.