Illinois vs Kentucky: state income tax, 2025
For reference household P1 (single, $60,000 of wages), Illinois charges $2,829or less and Kentucky charges $2,269or less. Both are bounded in the same direction, so the difference between them cannot be stated.
Both figures are a hypothetical full-year resident return for tax year 2025, over the same federal return, and count state income tax only. Neither is a relocation estimate: moving mid-year means two part-year returns, which this site does not figure. “Or less” means a mechanism the engine does not yet model would lower the figure; “or more” that it would raise it.
Six households, both states
| Household | Illinois | Kentucky | Illinois minus Kentucky |
|---|---|---|---|
| P1 Single, $60,000 of wages | $2,829or less | $2,269or less | not bounded |
| P2 Married filing jointly, $150,000, two children | $6,861or less | $5,869or less | not bounded |
| P3 Single, $85,000 wages + $15,000 long-term gain + $3,000 qualified dividends | $4,957or less | $3,989or less | not bounded |
| P4 Married retirees, $40,000 Social Security + $30,000 pension + $20,000 IRA, both 65+ | $0or less | $0or less | not bounded |
| P5 Head of household, $45,000, one child | $1,945or less | $1,669or less | not bounded |
| P6 Single, $1,200,000 of wages + $500,000 long-term gain | $84,150or less | $67,869or less | not bounded |
Full-year resident figures for 2025, state income tax only, with the same federal return in every column. Every figure is provisional. “Not shown” and “not figured” mean the engine will not state a number it cannot stand behind; hover for why.
Where the difference comes from
Illinois
- Where the return starts. Starts from federal adjusted gross income.
- Rate. A flat 4.95% on taxable income.35 ILCS 5/201; 2025 Form IL-1040 Instructions: "The Illinois income tax rate is 4.95 percent (.0495)." (checked 2026-08-05)
- Personal exemption. $2,850 per filer and $2,850 per dependant.35 ILCS 5/204; 2025 Form IL-1040 Instructions: "The personal exemption amount for tax year 2025 is $2,850." Line 10b and 10c each add $1,000 per box checked for age 65 or over and for blindness. (checked 2026-08-05)
- Excluded from income. Retirement income.2025 Form IL-1040 Instructions, Line 5: subtract federally taxed Social Security and retirement income from qualified employee benefit plans, IRAs and self-employed retirement plans reported on federal Form 1040 lines 4b and 5b, and Social Security and railroad retirement reported on line 6b. (checked 2026-08-05)
- Added to income. Municipal bond interest from other states.2025 Form IL-1040 Instructions, Line 2: add the federally tax-exempt interest and dividend income reported on federal Form 1040 line 2a. (checked 2026-08-05)
- Earned income credit. 20% of the federal credit, refundable.
Kentucky
- Where the return starts. Starts from federal adjusted gross income.
- Rate. A flat 4% on taxable income.KRS 141.020(2)(d); 2025 Form 740 line 12: "Tax Computation: Multiply line 11 by 4% (.04) or amount from Schedule J." (checked 2026-08-05)
- Standard deduction. $3,270 single, $3,270 married filing jointly.KRS 141.081; 2025 Form 740 line 10: "Nonitemizers: Enter $3,270 in Columns A and/or B." (checked 2026-08-05)
- Added to income. Municipal bond interest from other states.KRS 141.019(1)(c); 2025 Schedule M line 1: "Enter interest income from bonds issued by other states and their political subdivisions"; "Interest from securities of Kentucky and its political subdivisions is exempt." (checked 2026-10-20)
- Excluded from income. Retirement income.KRS 141.019(1)(l); 2025 Schedule M line 9 instructions: "The 2025 exclusion amount is 100 percent of taxable retirement benefits or $31,110, whichever is less. All pension and retirement income paid under a written retirement plan (qualified or unqualified) is eligible for exclusion." (checked 2026-08-05)
- Excluded from income. Social Security benefits.2025 Schedule M line 10: "Enter taxable amount of Social Security and Railroad Retirement Board benefits." (checked 2026-08-05)
- Local income tax. Levied locally in parts of the state, and not included in the figures above.
What this comparison leaves out
Mechanisms the engine does not model yet. Each one is named with the direction it would move the figure, which is where every “or less” above comes from.
Illinois
- Property tax and K-12 education expense credits (Schedule ICR) 35 ILCS 5/208, 5/201(m) — the figure is too high without it
- Illinois municipal bond and U.S. obligation subtractions (Schedule M) 35 ILCS 5/203(a)(2) — the figure is too high without it
- Credit for tax paid to another state (Schedule CR) 35 ILCS 5/601(b)(3) — the figure is too high without it
Kentucky
- Family Size Tax Credit where the return cannot settle family size or MGI (Schedule ITC Section C) KRS 141.066 — the figure is too high without it
- Kentucky-issuer share of tax-exempt interest added back on Schedule M line 1 KRS 141.019(1)(c) — the figure is too high without it
- Filing Status 2 — married, filing separately on a combined return KRS 141.180 — the figure is too high without it
- Kentucky itemized deductions beyond the entered mortgage interest and contributions (Schedule A) KRS 141.019(2) — the figure is too high without it
- Kentucky National Guard personal credit ($20 per member) KRS 141.020(3) — the figure is too high without it
- Schedule ITC Section A business incentive credits and the Education Tuition Tax Credit (Form 8863-K) KRS 141.0205, §141.069 — the figure is too high without it
- Credit for taxes paid to another state KRS 141.070 — the figure is too high without it
Taxes that are not income tax. Property tax, sales and excise taxes, and state payroll levies such as disability or paid-leave contributions are not counted here, and none of them is small. Federal tax is excluded because it is the same in both columns. A state income tax comparison is not a total tax burden comparison; see methodology.
Data status
Illinois. 2025 rules are provisional; engine coverage is implemented, with 3 mechanisms declared as not yet modelled. See the 2025 rate table.
Kentucky. 2025 rules are provisional; engine coverage is implemented, with 7 mechanisms declared as not yet modelled. See the 2025 rate table.
2026 state rules are not built yet, so this page compares 2025 only. Track status on the 2025 data status board.
Try it with your own return
The six households above are reference cases. Your own return will land differently. Compare Illinois and Kentucky over your own return — it stays in your browser.