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Illinois Self-Employment Tax Calculator

Estimate SE tax, federal and state tax, and a quarterly estimated-payment amount on 1099/self-employment income

Estimate only — not tax advice. Self-employment tax is 15.3% (12.4% Social Security + 2.9% Medicare) on 92.35% of net SE income, with half of it deducted from federal taxable income. Assumes this is your only income for the year — if you also have W-2 wages, results will run high (see methodology below). Does not model the 20% Qualified Business Income deduction. The quarterly figure is an even 4-way split of annual liability, not the IRS's actual (unevenly spaced) estimated-payment due dates.

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Illinois Paycheck Calculator FAQ

What is Illinois's state income tax rate?

Illinois charges a flat 4.95% income tax rate on all taxable income — the Illinois Constitution (art. IX, § 3) prohibits graduated rates. Each filer gets a $2,425 personal exemption in 2026.

Does Illinois tax retirement income?

No — Illinois does not tax Social Security, pension income, or 401(k)/IRA withdrawals, making it comparatively favorable for retirees despite the flat wage tax.

Does Illinois have local income tax?

No. Unlike Pennsylvania or Ohio, no Illinois city or county adds a separate local income tax on top of the state's flat 4.95% rate.

Methodology & Source

Illinois state tax figures sourced from Illinois Department of Revenue (https://tax.illinois.gov/), citing 35 ILCS 5/201 — flat 4.95% rate (Illinois Constitution art. IX, § 3 prohibits graduated rates). Federal brackets, standard deductions (single/MFJ/HoH), and FICA constants sourced from the IRS (Revenue Procedure 2025-32; married-filing-jointly Additional Medicare threshold of $250,000 is a separate, unindexed statutory figure). Illinois's married-filing-jointly and head-of-household figures have been independently verified against the source above.

Self-employment tax uses the statutory 15.3% rate (12.4% Social Security + 2.9% Medicare) on 92.35% of net self-employment income, with half of the SE tax deducted from federal taxable income above-the-line — per IRS Schedule SE (Form 1040) instructions, IRC §1401 and §164(f), 2026 edition. The 20% Qualified Business Income deduction (IRC §199A) is not modeled — it phases out by income and business type and is too state/entity-dependent to compute generically. This assumes the self-employment income is your only earnings for the year; if you also have W-2 wages, the Social Security wage-base cap and Additional Medicare threshold are actually based on your combined earnings, so this will overstate SE tax if you have significant wage income too.

This is an estimate based on standard single-filer federal, FICA, and IL state calculations. Actual withholding may differ based on your W-4 elections, pre-tax deductions (401k, health insurance), and other factors.

Guideline version: 2026-IL-v1 · Effective: 2017-07-01 · Last verified: 2026-07-26