Illinois Small Business Tax Guide — 2026
Income Tax Rate
4.95% flat rate
Sales Tax Rate
6.25% state + local (total typically 8% — 11%)
Filing Deadline
April 15 (matches federal deadline)
Illinois Income Tax
Illinois imposes a state income tax with rates of 4.95% flat rate. Self-employed individuals, freelancers, and sole proprietors pay this tax on their net business income in addition to federal income tax and federal self-employment tax (15.3%).
Self-Employment in Illinois
Illinois imposes a flat 4.95% income tax. Self-employed individuals also pay the Replacement Tax if operating as a partnership or S-Corp (1.5%). No separate SE tax for sole proprietors.
Estimated Tax Requirements
Quarterly estimated payments required if you expect to owe $1,000 or more. Standard federal due dates apply.
Illinois Deductions & Credits
- Illinois starts with federal AGI — most federal deductions flow through
- No standard deduction or personal exemption at state level
- Property tax credit: 5% of property taxes paid
- Education expense credit for qualifying expenses
Business Filing Fees
LLC: $150 formation + $75 annual report. Corporation: $150 formation + $75 annual report.
Key Facts About Illinois Taxes
- Illinois has a constitutionally mandated flat income tax — rate cannot be progressive without amendment
- Replacement Tax of 1.5% applies to S-Corps and partnerships
- Chicago area has some of the highest combined sales tax rates in the nation
- No deduction for retirement income — Illinois exempts it entirely
The Part Illinois Does Not Do For You
Whatever Illinois takes, it takes on your net profit — and net profit is just what you earned minus what you can prove you spent. The proving is on you, and it is where most of the money leaks out.
TaxTidy is where the proof lives. Photograph a receipt and it reads the vendor, the amount and the date in about three seconds, then files the expense on its Schedule C line. Nothing gets typed in twice, and nothing depends on you remembering a purchase from eight months ago.
Because Illinois wants its own return alongside the federal one, the same organized record does double duty — one set of receipts, sorted once, ready for whichever deadline comes first. Your Audit Readiness Score shows you how solid that record is before anyone else asks.
Frequently Asked Questions
What is Illinois's tax rate for freelancers?
Illinois has a flat 4.95% income tax rate. Sole proprietors pay this on net business income. S-Corps and partnerships also pay a 1.5% Replacement Tax at the entity level.
Does Illinois have a standard deduction?
No. Illinois does not offer a standard deduction or personal exemption. The state starts with your federal adjusted gross income.
When are Illinois estimated taxes due?
Quarterly on April 15, June 15, September 15, and January 15. Required if you expect to owe $1,000 or more.
Official source: Illinois Department of Revenue
TaxTidy provides expense organization tools based on the most current US tax law available to it. TaxTidy is not a CPA, Enrolled Agent, or licensed tax professional. All categorizations, deductions, and tax calculations are estimates. Please verify all data for accuracy and consult a certified tax professional before filing.
Start Tracking Your Illinois Business Expenses
Your first 25 scans are on us — free for life, no card required. Enough to sort this quarter's receipts by Schedule C line and see your Audit Readiness Score for the first time.
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