Illinois (IL) Self Employment Tax Calculator
Tax year: 2026 · Last updated 2026-06-22 · Source: IRS
Reviewed by CalcSumly Engineering Team, calculator authors and data architects · 2026-06-22
Your Schedule C net profit (income minus business expenses).
If you also had a job, enter wages already subject to Social Security.
Total tax (federal SE + IL income tax)
$14,839
Combined effective rate 18.5% of net profit · 2026 tax year
You owe about $11,304 in federal SE tax and $3,535 in Illinois income tax — a combined $14,839. You can deduct $5,652 from federal income tax.
How this Illinois self-employment tax calculator works
This calculator estimates your total tax on self-employment income in Illinois for 2026. It combines two distinct layers of tax:
- Federal self-employment tax (Schedule SE) — 15.3% on 92.35% of your net profit, split between Social Security (12.4%, capped at the $184,500 wage base) and Medicare (2.9%, no cap). An extra 0.9% Additional Medicare applies above $200,000 (single) or $250,000 (MFJ). The deductible half — 50% of the base SE tax — is then subtracted from your gross income to arrive at federal AGI.
- Illinois state income tax — Illinois taxes net income at a flat 4.95%. For W-2 employees, net income approximates federal AGI minus the Illinois personal exemption allowance ($2,925 per person in 2026). Pre-tax 401(k) deferrals reduce federal AGI and therefore reduce Illinois net income. The exemption phases out above $250,000 (single) / $500,000 (MFJ) in federal AGI.
Step-by-step calculation
- Net earnings: Net profit × 92.35% = SE tax base.
- Federal SE tax: Social Security + Medicare + Additional Medicare (if applicable).
- Deductible half: ½ × (Social Security + Medicare) — deducted above the line on Form 1040.
- Federal AGI from SE: Net profit − deductible half.
- Illinois taxable income: Federal AGI minus the Illinois standard deduction ($2,925 single).
- Illinois income tax: Flat 4.95% applied to Illinois taxable income.
Scope and limitations
What is excluded: Excludes Illinois local taxes and the 1.5% Personal Property Replacement Tax (PPRT) that applies to S-Corps and partnerships at entity level. SDI is not applicable in Illinois. Age-related additional exemption ($1,000 per qualifying condition) is excluded. This calculator models a single Schedule C filer with no other income sources. It does not include QBI deduction (20%), health insurance deductions, retirement plan contributions, tax credits, or itemized deductions. Consult a tax professional for your full return.
Use this for planning, not filing. Every rate and threshold is pulled from official IRS, SSA, and IL Dept. of Revenue — Income Tax Rates (4.95% flat rate) publications and re-checked each January.
Sources
- IRS — Self-Employment Tax (Schedule SE)
- SSA — 2026 Social Security wage base ($184,500)
- IRS — Topic 751 Additional Medicare Tax
- IRS — Rev. Proc. 2025-32 (2026 inflation adjustments)
- IRS — Form 1040-ES (Estimated Tax for Individuals)
- IRS Notice 2025-67 — 2026 Retirement Plan Limits (§415, §402(g), §401(a)(17))
- IRS — SEP Contribution Limits 2026 ($72,000)
- IRS Notice 2026-10 — 2026 Standard Mileage Rates (72.5 cents/mile)
- IRS Rev. Proc. 2013-13 — Home Office Simplified Method ($5/sqft, 300 sqft max)
- IRS Publication 946 (2026) — Section 179 Deduction ($2,560,000 limit; $32,000 SUV cap)
- IL Dept. of Revenue — Income Tax Rates (4.95% flat rate)
- IL Dept. of Revenue — What is the Illinois exemption allowance? ($2,925 per exemption, 2026)
Frequently asked questions
What is Illinois's income tax rate on self-employment income?+
Illinois has a flat 4.95% state income tax. Self-employed people subtract their personal exemption credit ($2,925 for 2026) from Illinois AGI to arrive at Illinois taxable income — though technically Illinois uses a credit structure rather than a deduction. The flat rate means every additional dollar of SE profit is taxed at exactly 4.95%, regardless of income level. Source: Illinois Department of Revenue.
Does Illinois tax the deductible half of SE tax?+
Illinois starts from federal AGI, so the deductible half of SE tax (which reduces federal AGI) also reduces Illinois taxable income. A $5,652 SE tax deduction at a $80,000 profit level saves roughly $280 in Illinois income tax ($5,652 × 4.95%), on top of the federal income tax savings.
What is self-employment tax?+
Self-employment (SE) tax is the Social Security and Medicare tax paid by freelancers, 1099 contractors, and sole proprietors. Employees split these costs with their employer (7.65% each); when you work for yourself you pay both halves — 15.3% total — on 92.35% of your net profit. It is separate from, and on top of, federal and state income tax.
Do I also owe Illinois state income tax on my self-employment income?+
Yes. In addition to federal SE tax, Illinois taxes self-employment net profit as ordinary income. This calculator shows both: the federal SE tax (Social Security + Medicare) and the estimated Illinois state income tax side by side, so you can see your true combined tax bill.
Can I deduct half of my self-employment tax?+
Yes — from federal income tax. You can deduct one half of your Social Security and Medicare SE tax as an above-the-line adjustment to income on Form 1040. This deductible half also reduces your federal AGI, which in turn reduces your state taxable income in most states (except Pennsylvania, which taxes gross compensation regardless).
How can I lower my self-employment tax?+
SE tax is based on net profit (gross revenue minus business expenses), so every legitimate business deduction reduces both your SE tax and your state income tax. Common deductions include home-office use ($5/sqft simplified method), equipment and software (Section 179), business mileage, and professional services. The standard deduction and QBI deduction reduce income tax only — not SE tax.
When do I pay self-employment tax?+
SE tax is paid through quarterly estimated payments (Form 1040-ES), due April 15, June 16, September 15, and January 15 for the prior year's fourth quarter. If you expect to owe $1,000 or more in federal tax after withholding, you generally must pay quarterly to avoid the IRS underpayment penalty. Most states that tax SE income have parallel quarterly estimated payment requirements.
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