Illinois Self-Employed Tax Calculator

Freelancers, 1099 contractors, and sole proprietors in Illinois: estimate your federal self-employment tax, income tax, and Illinois state tax — plus quarterly estimated payments.

Reading the results: The calculator below shows W-2 employee tax amounts. As a self-employed worker, multiply the FICA total by roughly 2× to approximate your Self-Employment (SE) tax, then add federal income tax and Illinois state tax. A dedicated SE calculator with quarterly breakdown is coming soon.

Your details

Gross pay

State

Filing status

Advanced (pre-tax deductions)

401(k) contribution (per period)

Health premium (pre-tax, per period)

Take-home$64,557per year

Monthly take-home$5,380

Bi-weekly$2,483

Effective tax rate24.0%

Marginal rate27.0%

Annual breakdown

Gross income
$85,000
Federal income tax(11.6%)
-$9,870
Social Security (6.2%)(6.2%)
-$5,270
Medicare (1.45%)(1.5%)
-$1,233
Illinois state tax(4.8%)
-$4,070
Take-home pay(75.9%)
$64,557

Calculations use projected 2026 IRS brackets, standard deduction, and FICA rates. Read full disclaimer.

Self-employment tax in Illinois: the basics

If you earn $400+ in net self-employment income in Illinois, you owe Self-Employment tax (15.3%): 12.4% for Social Security (on net earnings up to $184,500 in 2026) + 2.9% for Medicare (no cap). An additional 0.9% Medicare surtax kicks in above $200,000 (single) / $250,000 (MFJ).

Unlike W-2 employees who split FICA 50/50 with their employer, you pay both halves. The good news: you deduct 50% of SE tax on your federal 1040 as an above-the-line adjustment.

Quarterly estimated tax schedule

Federal quarterly deadlines for tax year 2026:

Q1 (Jan 1 – Mar 31): due April 15, 2026
Q2 (Apr 1 – May 31): due June 16, 2026
Q3 (Jun 1 – Aug 31): due September 15, 2026
Q4 (Sep 1 – Dec 31): due January 15, 2027

Missing payments triggers the IRS "underpayment penalty" (~5–8% annualized interest).

Illinois specific considerations

Illinois uses a flat 4.95% income tax rate. A $2,775 per-person exemption lowers taxable income.

Self-employed workers in Illinois pay state income tax on their net business income (after deducting ordinary business expenses, home office, mileage, etc.). File Schedule SE (federal) plus Illinois's equivalent state return. Check Illinois Department of Revenue for exact forms.

Deductions every Illinois freelancer should know

Home office — simplified: $5 × sq ft (max 300 sq ft = $1,500)
Mileage — $0.70/mile (2025 IRS standard rate, likely increasing for 2026)
Health insurance premiums — 100% deductible for self-employed (above-the-line)
SEP-IRA / Solo 401(k) — up to 25% of net SE income (SEP) or $70,000 total (Solo 401(k) 2025)
QBI deduction — up to 20% of qualified business income (Section 199A)
Business meals — 50% deductible (must be with client/business purpose)

Self-employed tax FAQ for Illinois

How is self-employment tax different from regular W-2 employment in Illinois?

Self-employed individuals in Illinois pay the full 15.3% SE tax (12.4% Social Security + 2.9% Medicare) themselves — W-2 employees only pay half (7.65%), with the employer paying the other half. You can deduct 50% of your SE tax when calculating your federal income tax. The calculator above shows W-2 estimates; multiply FICA by ~2x to approximate SE tax exposure.

Do I need to pay quarterly estimated taxes in Illinois?

If you expect to owe $1,000 or more in federal tax (after withholdings), yes. Quarterly estimated tax deadlines are April 15, June 15, September 15, and January 15. Illinois also requires quarterly state estimated payments if you owe $500+ in state tax.

What expenses can I deduct as a Illinois freelancer?

Common deductions include: home office (simplified method = $5 per sq ft up to 300 sq ft), business mileage ($0.70 per mile in 2025), health insurance premiums, retirement contributions (SEP-IRA, Solo 401(k)), continuing education, software subscriptions, phone/internet proportional to business use. Keep receipts and records for all of them.

Should I form an LLC or S-Corp in Illinois?

For freelancers earning under ~$80K, a single-member LLC (taxed as sole proprietor by default) is usually enough and simpler. Above that, an S-Corp election can save on SE tax by paying yourself a reasonable salary + distributions. Illinois has standard LLC filing requirements — expect annual fees and paperwork. Consult a CPA before deciding.

How much should I set aside for taxes as a 1099 worker in Illinois?

A safe rule of thumb is 25–30% of gross income set aside in a separate account. This covers federal income tax (10–24% for most freelancers), SE tax (15.3%), and Illinois's flat 4.95% state tax. Higher earners may need to set aside 35–40%.

Illinois paycheck calculator (W-2 employees)

Salaried or hourly? Use the main calculator for accurate W-2 estimates.

Main Illinois calculator →