Illinois tax forms & filing.

Things to know about filing in Illinois

• Illinois has reciprocity agreements with Iowa, Kentucky, Michigan, and Wisconsin — if you live in IL and work in one of those states (or vice versa), wages are taxed only by your resident state. No nonresident return required for those reciprocity neighbors.
• Illinois has a separate Chicago property tax and Cook County tax structure that affects city residents but is not part of the state return. The state return is just IL.
• Illinois has a state estate tax with a threshold significantly lower than the federal estate tax. Illinois-resident estates above the state threshold but below the federal threshold still owe Illinois estate tax.
• Illinois does not tax retirement income (Social Security, qualified pensions, 401(k) and IRA distributions) — this is one of the most retirement-friendly state tax treatments in the country.

Illinois retirement income exclusion — the most generous in the country

Illinois excludes essentially all federally-recognized retirement income from state tax: Social Security benefits, qualified employer pensions, 401(k) distributions, IRA distributions (including Roth conversions taxed federally), 403(b) distributions, government pensions, and railroad retirement income. There is no income limit or phase-out — the exclusion applies regardless of total retirement income.

Practical effect: an Illinois retiree with $200,000 in combined pension, 401(k), and Social Security income pays no Illinois income tax on any of it. Only investment income (interest, dividends, capital gains not from retirement accounts) and wages from continued employment are subject to Illinois tax.

This is one of the most retirement-friendly tax treatments in the country and frequently a factor in retirement-state decisions. It does mean that interest from non-retirement bonds, dividend income from a taxable brokerage account, and Roth conversions sourced from non-retirement assets ARE Illinois-taxable — even for retirees.

Illinois constitutional flat tax — what it means and doesn't mean

Illinois's flat individual income tax rate is fixed by the state constitution. In 2020, Illinois voters rejected a ballot measure that would have allowed progressive brackets — keeping the constitutional flat-rate requirement in place. Any future change to progressive taxation would require another constitutional amendment.

The flat rate applies to wages, business income, rental income, capital gains (no preferential rate), and most other income types. There's no AMT, no surtax, and no income-based bracket structure.

Combined with the broad retirement income exclusion, Illinois ends up being a high-tax state for working-age high earners (compared to flat-tax peers Indiana and Pennsylvania) but a low-tax state for retirees with similar total income.

Where's my refund?

The Illinois Department of Revenue runs the official refund-status tracker. You'll need your Social Security number, filing status, and exact refund amount (in some cases, the tax year and a return-amount input).

Check your Illinois refund status →

Multi-state considerations

If you lived or worked in more than one state during the tax year, you typically file a part-year resident return in each state. If you live in one state and work in another, you usually file as a resident where you live and as a nonresident in the work state — claiming a credit on the resident return for taxes paid to the work state. Reciprocity agreements between some neighboring states change this default; we map this out at intake.

Illinois-specific multi-state nuances are addressed in the quirks list above when they apply.

Get the current-year forms

State tax rates, brackets, and forms change every year. We point to the Illinois Department of Revenue as the authoritative source for current-year information. Form numbers above are stable; rates, deduction amounts, and credit limits are not — always verify before relying on a specific dollar amount.

Open the Illinois Department of Revenue website →