Calculate how Kentucky Form K-4 state withholding allowances and federal Form W-4 elections alter take-home pay on your Kentucky paycheck.
Federal Form W-4 elections dictate your federal income tax withholding line by line, but they do not alter Kentucky's flat 3.5% state income tax. Entering dependent credits in Step 3 reduces your federal withholding dollar-for-dollar, while extra withholding in Step 4(c) directly increases tax withheld each pay period to eliminate an underpayment penalty in April.
Kentucky · 2026 tax year · salaried or hourly
Your W-4 details, withholding, and FICA exemptions.
When starting a job or adjusting payroll withholding in Kentucky, new employees must navigate two completely separate forms: IRS Form W-4 (federal) and Kentucky Department of Revenue Form K-4 (Form 42A804).
| Feature | Kentucky Form K-4 (42A804) | Federal Form W-4 (IRS) |
|---|---|---|
| Taxing Authority | Kentucky Department of Revenue (Frankfort) | Internal Revenue Service (Federal) |
| Primary Function | State income tax withholding certificate & exemption claim | Federal income tax withholding calculation |
| Allowances System | Single checkbox certificate for specific statutory exemptions | Allowances eliminated in 2020 (uses exact dollar credits) |
| State Rate Structure | Flat 3.5% (2026 statutory rate) | 7 progressive marginal brackets (10% to 37%) |
| Standard Deduction | $3,360 (automatically built into state withholding formula) | $15,000 (Single) / $30,000 (Married Jointly) for 2026 |
| Additional Withholding | Line 2 allows an extra flat dollar amount per paycheck | Step 4(c) allows an extra flat dollar amount per paycheck |
| Reciprocal State Commuters | Claim Box 4 with Form 42A809 (IN, OH, IL, WV, VA, MI, WI) | Not applicable (federal income tax applies universally) |
*Note: Filing an exemption on Kentucky Form K-4 only waives the 3.5% Kentucky state income tax. It does NOT exempt your wages from Federal Income Tax, Social Security (6.2%), Medicare (1.45%), or local city/county occupational taxes.
Unlike the complex multi-step federal W-4, Kentucky Form K-4 is essentially an exemption certificate. Under 2026 Kentucky law, only employees meeting one of these four statutory conditions should claim exempt:
If you work more than one job in Kentucky, or are married filing jointly where both spouses earn income, here is how both forms coordinate:
Answer 3 simple questions to find out whether you qualify to claim exempt on Kentucky Form 42A804, and see the exact net impact on your paystub.
Four questions, drawn from the exemption instructions on form 42A804 (K-4)(12-2025). Nothing you enter leaves your browser.
A K-4 exemption stops Kentucky state withholding and nothing else. Federal tax, Social Security, Medicare and your city’s occupational tax all carry on. Here is the size of each.
| Annual | Normal withholding | With a K-4 exemption |
|---|---|---|
| Federal income tax | $4,420.00 | $4,420.00 |
| Kentucky state tax (3.5%) | $1,807.40 | $0.00 |
| Social Security | $3,410.00 | $3,410.00 |
| Medicare | $797.50 | $797.50 |
| Local occupational tax — Louisville 2.20% | $1,210.00 | $1,210.00 |
| Take-home pay | $43,355.10 | $45,162.50 |
The exemption is worth $1,807.40 a year. That is the entire effect of checking a box — the Kentucky state line, and nothing more.
$9,837.50 is still withheld. Federal tax, FICA and Louisville's occupational tax are untouched by the K-4. Local occupational tax follows where the work happens, not where you are domiciled, so even a reciprocal-state commuter or a Fort Campbell nonresident keeps paying it in full.
Put another way: the exemption removes about 16% of the tax withheld from your pay. “Exempt” on this form has never meant tax-free.
Estimates for the 2026 tax year, filing single with no pre-tax deductions. The current form, revision (12-2025), prints “a flat 3.5% rate with a standard deduction allowance of $3,360” — the same figures used above and by your employer’s payroll system. If the copy in front of you says 4% and $3,160, it is the superseded 2024 form; get the current one. Not tax advice.
The post-2020 IRS Form W-4 completely eliminated withholding allowances, replacing them with exact annual dollar amounts for dependent credits, other income, and extra deductions.
Claiming a $2,000 child tax credit on W-4 Step 3 reduces federal paycheck withholding by roughly $76.92 on every bi-weekly pay stub.
Kentucky state tax ignores federal W-4 dependent entries, applying a flat 3.5% statutory rate after the Kentucky standard deduction ($3,360 for 2026).
If you work multiple jobs or have an employed spouse, checking the Step 2(c) box recalculates withholding at higher marginal brackets to avoid owing taxes in April.
1Enter your annual salary or hourly rate and select your regular pay frequency (weekly, bi-weekly, semi-monthly, or monthly).
2Open Federal Taxes to mirror your Form W-4: select your filing status, check Step 2 for multiple jobs, enter Step 3 dependent credits, and insert Step 4 extra withholding.
3Compare your simulated take-home pay against your recent paycheck stub to verify your employer's withholding matches your tax goals.
Kentucky employers use federal Form W-4 solely for federal income tax withholding. For Kentucky state taxes, withholding is calculated using Kentucky's flat 3.5% formula and standard deduction. If you qualify for specific state-level withholding exemptions, your employer will provide Kentucky Form K-4.
Step 3 divides your total annual dependent tax credits ($2,000 per qualifying child under 17, $500 for other dependents) evenly across your annual pay periods. For a bi-weekly worker claiming two children ($4,000 total), federal withholding drops by $153.85 per paycheck, putting that money straight into net pay.
You should check Step 2(c) if you work more than one job at the same time, or if you are married filing jointly and both spouses work and earn roughly similar compensation. Checking Step 2 applies tax withholding brackets symmetrically so you do not underpay federal tax across higher tax bands.
Step 4(c) instructs payroll to withhold an exact additional dollar amount from every single paycheck. Employees with non-wage earnings (freelance 1099 income, capital gains, interest, dividends) commonly use Step 4(c) so their W-2 wages cover estimated quarterly tax requirements automatically.
No. Form W-4 only alters the timing of tax collection during the year, not your ultimate legal tax obligation. If you withhold too little, you will owe the IRS plus potential underpayment penalties; if you withhold too much, you receive a refund without interest.