Illinois state income tax rate 2027

A flat rate written into the statute

Section 201 of the Illinois Income Tax Act imposes the individual rate as an amount equal to 4.95% of net income "for taxable years beginning on or after July 1, 2017". That paragraph has no end date and no scheduled step, so the projected 2027 rate is the same 4.95%. A change would need an amendment to the Act, and none is enacted in the text read on November 1, 2026.

Exemptions, not a standard deduction

Illinois starts from federal adjusted gross income and subtracts an exemption allowance for you, your spouse and each dependent. Section 204 sets the base at $2,050 plus a cost-of-living adjustment for years through 2028. Tax Foundation's 2026 table lists the adjusted amount as $2,925 per person, which is the figure this page uses for 2027 (the 2027 adjusted amount is not yet published). Taxpayers with high income lose the exemption; Tax Foundation notes the cutoff as federal adjusted gross income above $250,000 for single filers and $500,000 for joint filers.

Worked example

Single, $75,000 of wages, one $2,925 exemption: taxable income $72,075 and tax $3,567.71 at 4.95%, an effective 4.76% of wages. A couple with $120,000 of wages and two dependents has four exemptions, $11,700, so taxable income is $108,300 and tax is $5,360.85. Each additional dependent reduces tax by about $145 (4.95% of $2,925).

What is not in the number

Credits and subtractions that move the final bill are not modelled, and the calculator treats wages only. For net pay, which also includes federal tax and FICA, use the Illinois paycheck calculator.

Who this is for, and what it does not cover

It is for employees and planners estimating Illinois state income tax on wages for 2027. It does not cover local income taxes, tax credits, retirement or investment income, self-employment tax, federal income tax or payroll taxes, and it does not file or submit anything. The result changes if you enter a different rate, so use the rate box when the state announces a final 2027 figure.

FAQ

What is the Illinois state income tax rate for 2027?

The Illinois Income Tax Act sets 4.95% of net income for individuals for taxable years beginning on or after July 1, 2017, with no end date, so 2027 is projected at 4.95%.

Is Illinois income tax a flat tax?

Yes. One rate, 4.95%, applies to all net income of individuals, trusts and estates.

Does Illinois have a standard deduction?

No. It uses an exemption allowance for the taxpayer, spouse and dependents. Section 204 sets $2,050 plus a cost-of-living adjustment through 2028; Tax Foundation lists $2,925 per person for 2026.

Who loses the Illinois exemption?

Tax Foundation notes the exemption is unavailable when federal adjusted gross income is above $250,000 for single filers or $500,000 for joint filers.

Could Illinois change the rate before 2027?

Only by amending the Act. The statute text read on November 1, 2026 contains no scheduled change, so the figure here is a projection, not a guarantee.

Is this my final 2027 Illinois tax?

No. It is a projection using the 2026 exemption amount. Credits, retirement-income subtractions and other adjustments are not modelled.

Sources

Retrieved 2026-11-01. Each link was opened and checked against the claim next to it; where a page blocks automated readers a dated archive copy is named.

• 35 ILCS 5/201 (Illinois General Assembly): The 4.95% individual rate for taxable years beginning on or after July 1, 2017.
• 35 ILCS 5/204 (Illinois General Assembly): The exemption allowance base of $2,050 plus cost-of-living adjustment through 2028.
• Tax Foundation: State Individual Income Tax Rates and Brackets, 2026: The $2,925 per-person exemption amount for 2026 and the high-income cutoff.