Kentucky’s income tax has become a moving target in the best way for taxpayers: a single flat rate that the legislature keeps ratcheting down — 5% before 2023, 4.5% in 2023, 4.0% for 2024 and 2025, and 3.5% from the 2026 tax year. This calculator subtracts the Kentucky standard deduction (or your itemized total) from adjusted gross income and applies the flat rate, showing tax due and your effective rate. Current-year forms and rates are published by the Kentucky Department of Revenue.
The whole computation in three lines
deduction = max(standard deduction, itemized total)
taxable = Kentucky AGI − deduction
tax = taxable × flat rate (4.0% for 2024-25; 3.5% from 2026)Because the rate is flat, the marginal rate and the effective rate on taxable income are identical; only the deduction pulls your effective rate on gross income below the headline number. Kentucky grants no per-person exemption amounts — the standard deduction ($3,160 for 2024, indexed annually) is the main subtraction, and unusually, it is the same for every filing status: joint filers do not get double, though each spouse applies their own deduction on a combined return.
The rate trajectory, by statute
| Tax year | Flat rate | Status |
|---|---|---|
| 2022 and earlier | 5.0% | historical |
| 2023 | 4.5% | historical |
| 2024–2025 | 4.0% | in force |
| 2026 onward | 3.5% | enacted |
The mechanism, in KRS 141.020 as amended, permits a 0.5-point cut whenever state budget-reserve and revenue conditions are met, subject to legislative enactment — that is how each step above happened, and why any further cuts below 3.5% require both triggers and a new bill. When planning ahead more than a year, verify the rate on the current Form 740 instructions.
Worked example
A single filer with $60,000 of Kentucky AGI in the 2024 tax year:
- Standard deduction: $3,160
- Taxable income: 60,000 − 3,160 = $56,840
- Kentucky tax: 56,840 × 4.0% = $2,273.60
- Effective rate vs. gross AGI: 2,273.60 ÷ 60,000 = 3.79%
Run the same numbers at the 2026 rate of 3.5% and the bill drops to $1,989.40 — a $284 saving with no change in income. For a joint return with $60,000 of combined income, each spouse’s own $3,160 deduction applies against their own income on the combined-return columns, so the arithmetic matches when income is all on one side.
What Kentucky doesn’t tax — and what it taxes that you may not expect
- Social Security benefits are fully exempt from Kentucky tax.
- Pension and retirement income enjoys a substantial exclusion (a per-person annual amount; amounts above it are taxable) — retirees should use the dedicated retirement calculator.
- Active-duty military pay is exempt.
- On the other side, Kentucky taxes most wages, business, and investment income identically — there is no preferential capital-gains rate at the state level. Gains that got the lower federal rate are plain taxable income to Kentucky.
Low-income households may also qualify for Kentucky’s family size tax credit, which phases out a percentage of the tax below income thresholds tied to the federal poverty level — a detail worth checking in the Form 740 instructions if household income is modest.
The local occupational tax caveat
The flat state rate is not the whole income-tax story in Kentucky. Many cities and counties levy occupational license taxes on wages and net profits earned within their borders — Louisville Metro around 2.2% (resident rate) and Lexington-Fayette 2.25% are the biggest examples, and many smaller municipalities charge 1-2%. These apply to gross earnings with no standard deduction and are filed separately from Form 740. A Louisville earner’s true combined state-plus-local income tax rate in 2024 was therefore closer to 6.2% than 4.0% — this calculator covers the state layer only.
Edge cases
Part-year residents and nonresidents file Form 740-NP and apportion — the flat rate applies only to Kentucky-source income. Self-employment income passes through at the same flat rate, but remember the separate federal SE tax (15.3%) and quarterly estimated payments. Itemizing at the state level is rare now: with a deduction threshold this low, only taxpayers with large charitable or mortgage-interest positions exceed the standard amount, and Kentucky’s itemized rules differ from the federal Schedule A (for instance, state income taxes paid are not deductible on the Kentucky return).
Sources
- Kentucky Department of Revenue — individual income tax
- Kentucky DOR — current-year forms (Form 740 instructions)
Estimate only — not tax advice. Confirm the current-year rate, deduction, and credits against the Form 740 instructions before filing.