Illinois Tax Guide (2026)
Comprehensive statutory analysis of Illinois individual income tax rates, Department of Revenue filing forms, extension guidelines, telecommuting sourcing rules, and pass-through entity tax provisions.
Key Statutory Tax Parameters (Illinois, 2026)
2026 Legislative & Statutory Highlights
The Illinois Constitution mandates a flat individual income tax rate, currently set at 4.95%. Illinois does not provide a standard deduction; instead, taxpayers receive a basic personal exemption allowance (inflation-adjusted around $2,775), which phases out completely for single filers with AGI over $250,000 ($500,000 married). Illinois offers a popular 5.0% property tax credit for primary residential property taxes paid.
Illinois operates a flat personal income tax schedule with a statutory flat rate of 5.0%. Tax parameters are indexed annually or enacted through state legislative sessions. Taxpayers should ensure that adjustments for federal bonus depreciation, Section 179 expensing, and Net Operating Loss (NOL) carryforwards follow Illinois's specific rolling or static Internal Revenue Code conformity date.
Filing Forms, Deadlines & Extension Guidelines
Multi-State Workers & Telecommuting Sourcing Rules
Illinois taxes residents on all income. Nonresidents working physically in Illinois for more than 30 working days are subject to Illinois nonresident withholding. Illinois maintains reciprocal tax agreements with Iowa, Kentucky, Michigan, and Wisconsin, exempting cross-border commuting workers from Illinois withholding.
Pass-Through Entity (PTE) Tax & Small Business Rules
Illinois offers an elective Pass-Through Entity Tax (PTE Tax) at a rate of 4.95%, allowing S-corporations and partnerships to deduct state tax payments at the federal level.
Estate & Inheritance Tax
Illinois imposes a state estate tax on estates exceeding $4,000,000, with tax rates graduating from 0.8% to 16.0%. Unlike the federal estate tax, the Illinois $4M exemption is not indexed for inflation.
Local & County Taxes
Local municipal earned income taxes are prohibited under the Illinois state constitution.
Worked Tax Example: $120,000 W-2 Earner in Illinois
A single professional in Chicago earning $120,000 in taxable income pays approximately $5,800 in Illinois state income tax under the 4.95% flat rate (net of basic personal exemptions), an effective state rate of 4.83%.
Calculate Your 2026 Illinois Tax Liability
Enter your taxable income, filing status, and municipal details below to calculate your customized state tax liability and print your executive summary.
Single flat rate 4.95% on all taxable income. Reciprocity with IA, KY, MI, WI.
2026 Executive Illinois State Tax Audit Summary
Not tax, legal, or financial advice
FiscTalk provides general educational information from public sources. Your tax results depend on the full set of facts, your filing history, and the jurisdiction-specific rules that shift yearly. Before filing or making decisions, consult a licensed CPA, EA, or attorney. FiscTalk is not a fiduciary and is not affiliated with the IRS or any state agency.
Sources & methodology
Frequently Asked Questions: Illinois Taxes
Source-verified — not professional advice
Every figure on this page is checked in-house against its primary source — IRS revenue procedures and publications, state Departments of Revenue, and the text of the underlying statute — before publication. Last reviewed 2026-10-20. The full source list is at the bottom of this page. If you spot an error, see our corrections & standards policy.
Not tax, legal, or financial advice
FiscTalk provides general educational information from public sources. Your tax results depend on the full set of facts, your filing history, and the jurisdiction-specific rules that shift yearly. Before filing or making decisions, consult a licensed CPA, EA, or attorney. FiscTalk is not a fiduciary and is not affiliated with the IRS or any state agency.
Sources & methodology