PiggySelf-Employment Tax in Illinois (2026)
flat / exact
Illinois taxes income at a single flat rate of 4.95%, which makes it one of the easier states to plan for: there are no brackets to climb, so an extra $1,000 of profit is taxed at the same rate as your first $1,000. The federal self-employment tax of 15.3% sits on top of that and is unaffected by where you live.
The federal part is the same everywhere
Self-employment tax replaces the payroll taxes an employer would otherwise split with you. As a freelancer you pay both halves: 12.4% for Social Security, on earnings up to the $184,500 wage base, and 2.9% for Medicare with no cap. Together that is 15.3%, charged on 92.35% of your net profit rather than all of it. See SE tax vs employee FICA and 2026 tax constants for the sourced figures.
At $100,000 of net profit federal SE tax is $14,129.55 in Illinois — exactly as it would be in any other state.
What Illinois adds
flat / exact State model quality matches the freelancer tax estimator — statutory math on a profit proxy, not a filed state return.
Illinois flat individual income tax 4.95%. The estimator marks IL as flat / exact — an honest quality badge, not a coarse guess dressed up as precision.
Chicago / local notes
Illinois uses a true flat rate, so planning percentages stay stable as profit rises. Chicago and some municipalities have other business fees; they are not a second personal income-tax bracket table. Illinois estimated payments are separate from federal 1040-ES.
What the two look like together
| Net profit | Federal SE tax | State income tax* | SE as % of profit | SE + state |
|---|---|---|---|---|
| $40,000 | $5,651.82 | $1,840 | 14.1% | $7,492 |
| $75,000 | $10,597.16 | $3,450 | 14.1% | $14,047 |
| $120,000 | $16,955.46 | $5,520 | 14.1% | $22,476 |
* Illinois flat 4.95% on profit after SE-half (no exemptions). Educational estimate — not tax advice.
Worked example: $80,000 profit in Illinois
Single filer, $80,000 Schedule C net profit, no other earned income:
- Federal SE tax: $11,304
- Illinois income tax (flat / exact): $3,680 (4.6% of profit)
- SE + state subtotal: $14,984 — before federal income tax and QBI
Because Illinois is flat, the percentage does not climb with a strong Q4 — only the dollars do. Still recalculate federal income tax and SE as profit grows.
Cross-check with the freelancer tax estimator and
2026 set-aside study (state_code=IL).
Quarterly payments
State-specific dates and envelopes: quarterly estimated taxes in Illinois.
Federal estimated payments still apply if you expect to owe $1,000 or more. Use the safe harbor calculator and quarterly deadlines. Add Illinois estimated payments on the state schedule when required.
Frequently asked questions
What is the self-employment tax rate in Illinois?
The self-employment tax rate is 15.3% and it is federal, so it is the same in Illinois as everywhere else. Illinois separately taxes income at a flat 4.95%.
Is the 4.95% flat rate on top of the 15.3%?
Effectively yes, though they are calculated differently and on different bases. The self-employment tax is federal and applies to 92.35% of your net profit. The state tax is a separate calculation starting from your state taxable income.
Do I make quarterly payments to Illinois as well as the IRS?
Usually yes. Most states with an income tax expect estimated payments from the self-employed on a similar schedule to the IRS. Check Illinois's revenue department for the exact thresholds, since they differ from the federal $1,000 rule.
Work out your own numbers
- Freelancer Tax Estimator — pick Illinois (IL); quality badge shows on the result.
- Self-Employment Tax Calculator — federal 15.3% only.
- 2026 set-aside study — filter CSV rows by
state_code=IL. - Set-aside by income — federal-leaning planning bands.
- SE tax vs employee FICA — why “15.3% of profit” is wrong.
- Methodology · 2026 tax constants — sources and dual-impl checks.
- All states · State comparison tool.