Illinois Tax Guide

⚠️ Important Disclaimer

This guide is for general informational purposes only and provides simplified overviews and estimates. It does not provide tax, legal, payroll, accounting, or financial advice.

Tax rules can change, and actual paycheck amounts may vary based on your employer, benefit elections, filing status, local taxes, deductions, credits, garnishments, and withholding elections. This guide does not cover every possible tax scenario.

For personalized tax advice, please consult a qualified tax professional.

For official guidance, review materials from the Illinois Department of Revenue and the Internal Revenue Service (IRS).

Last reviewed: June 2026

Illinois at a Glance

Illinois has a constitutionally mandated flat income tax rate of 4.95% on all taxable income. Rather than a standard deduction, Illinois provides personal exemptions of $2,875 per person plus $2,875 per dependent.

Illinois stands out as one of the few states that does not tax any retirement income — Social Security, pensions, and 401(k)/IRA distributions are all exempt from state income tax.

Key Tax Facts for Illinois

State Income Tax

Flat 4.95%

Federal Brackets

10% – 37%

Social Security

6.2%

Medicare

1.45%

SS Wage Base

$184,500

Personal Exemption

$2,875 / $5,750

Illinois Income Tax Brackets (2026)

Illinois has a flat income tax rate of Flat 4.95%. All taxable income is taxed at the same rate regardless of how much you earn.

How Your Illinois Paycheck Is Calculated

Every paycheck goes through the same basic pipeline from gross pay to the net amount that hits your bank account:

Gross Pay — Your total earnings for the pay period. For hourly workers this is (hours × rate) plus any overtime or double-time premiums. For salaried employees it’s your annual salary divided by the number of pay periods.
Pre-Tax Deductions — Contributions to 401(k), 403(b), HSA, or FSA are subtracted before income taxes are calculated. These lower your taxable wages but Social Security and Medicare still apply to the full gross in most cases.
Federal Income Tax — Withheld using the IRS Publication 15-T percentage method based on your W-4 filing status, credits, and additional withholding elections. For 2026, rates range from 10% to 37%.
State Income Tax — Illinois withholds state income tax at rates of Flat 4.95% based on your annualized income and filing status.
FICA Taxes — Social Security (6.2% on wages up to $184,500) and Medicare (1.45% on all wages). If your year-to-date earnings exceed the Social Security wage base, that portion stops being withheld.
Net Pay (Take-Home) — What’s left after all taxes and deductions. This is the amount deposited into your account each pay period.

Good to Know

Review your W-4 periodically. If you consistently receive a large refund, you may be over-withholding. Consider reviewing your W-4 Step 3 credits or Step 4(b) deductions to better align your withholding with your actual tax liability. The IRS Tax Withholding Estimator can help.
Benefits of contributing to a 401(k) or 403(b). Pre-tax retirement contributions can reduce your federal and state taxable income for the year. Even a modest percentage — say 3% to 6% — may noticeably lower your tax withholding while building long-term savings. Consult your plan administrator or a financial advisor for guidance.
Benefits of an HSA if you’re eligible. Health Savings Accounts offer a rare triple tax advantage — contributions lower your taxable income now, the balance grows tax-free, and withdrawals for qualified medical expenses are also tax-free. If you’re enrolled in a qualifying high-deductible health plan, an HSA is one of the most tax-efficient savings tools available.
Illinois tax note. Illinois has a flat income tax rate of 4.95%, mandated by the state constitution to be a single rate.
Illinois tax note. Illinois uses personal exemptions ($2,875 per person) rather than a standard deduction. Dependents also receive $2,875 each.
Illinois tax note. Illinois does not tax retirement income, including Social Security, pensions, and 401(k)/IRA distributions.

Frequently Asked Questions

What is Illinois’s income tax rate?

Illinois has a constitutionally mandated flat income tax rate of 4.95% on all taxable income.

Does Illinois have a standard deduction?

No. Illinois uses personal exemptions instead: $2,875 per person (single or each spouse) plus $2,875 per dependent.

Does Illinois tax retirement income?

No. Illinois does not tax Social Security benefits, pension income, or 401(k)/IRA distributions at the state level.

Sources

The information in this guide is based on the following official and publicly available sources. Always verify current rates and rules before making financial decisions.