Kentucky Bonus Calculator
Bonus Details
Federal W-4 Settings
Kentucky Withholding (Form K-4)
Deductions (Per Regular Paycheck)
Year-To-Date Data (Optional, Improves Accuracy)
Your Bonus Estimate
- Bonuses are not taxed at a special bonus rate when you file. They are ordinary income taxed at your regular marginal rate.
- The 22 percent federal flat rate is simply a withholding method employers use on supplemental wages paid separately. It is not a tax rate.
- Kentucky has a flat 4.0 percent income tax rate for 2025. Your bonus is taxed at this same rate whether paid separately or combined with regular wages.
- The aggregate method combines your bonus with regular wages and applies the standard deduction. The bonus portion equals the difference between combined withholding and regular-only withholding.
- Many Kentucky cities and counties levy local occupational license taxes (typically 1-2.5%) on wages earned within their jurisdiction.
- When you file your return, your total annual income determines your true liability. Over-withholding on the bonus becomes part of your refund. Under-withholding becomes tax due.
- Gross-up mode solves for the gross bonus your employer must pay so your take-home equals the target you enter.
What Is the Kentucky Bonus Calculator?
The Kentucky Bonus Calculator is a payroll withholding estimator based on the 2025 federal and Kentucky tax settings programmed into the tool. It can start with either a gross bonus or a desired take-home amount. The calculation uses your salary, pay frequency, withholding methods, federal W-4 settings, Kentucky deduction, local occupational tax rate, paycheck deductions, and optional year-to-date payroll information.
A Kentucky bonus calculator estimates bonus take-home by subtracting federal income tax withholding, Kentucky withholding, Social Security, Medicare, Additional Medicare withholding when applicable, and an entered local occupational tax. It can also work backward to estimate the gross bonus required for a specific after-withholding target.
The results include a bonus withholding breakdown, effective withholding rate, full-pay-period take-home pay, and an annual tax snapshot. The tool also compares the selected federal and Kentucky bonus withholding methods with their alternative methods.
How the Kentucky Bonus Calculator Withholding Method Works
The calculator starts with the gross bonus and subtracts every withholding amount assigned to that bonus. Its main take-home calculation is:
- B is the gross bonus.
- F is federal income tax withheld from the bonus.
- SS is Social Security withholding assigned to the bonus.
- M is Medicare withholding on the bonus.
- AM is Additional Medicare withholding assigned to the bonus.
- K is Kentucky income tax withheld from the bonus.
- L is local occupational tax on the bonus using the rate you enter.
Under the federal flat method, the code applies 22% while cumulative supplemental wages remain within $1,000,000. Any portion above that threshold uses 37%.
Under the Kentucky flat method, the calculator applies 4% directly to the bonus:
The entered local occupational tax rate is also applied directly to the bonus:
Social Security is 6.2% on applicable wages remaining below the programmed $176,100 wage base. Medicare is 1.45% of the bonus. Additional Medicare withholding is 0.9% of the wages that push year-to-date Medicare wages above $200,000.
With an aggregate federal or Kentucky method, the calculator adds the bonus to regular taxable wages for the pay period. It calculates withholding on the combined amount, calculates regular-only withholding, and assigns the difference to the bonus.
Worked Example
Assume a $5,000 gross bonus, a $75,000 annual salary, biweekly pay, the federal flat method, and the Kentucky flat method. Also assume no local occupational tax and no prior year-to-date Social Security or Medicare wages.
- Federal bonus withholding: $5,000 × 22% = $1,100.
- Kentucky bonus withholding: $5,000 × 4% = $200.
- Social Security on the bonus: $5,000 × 6.2% = $310.
- Medicare on the bonus: $5,000 × 1.45% = $72.50.
- Additional Medicare withholding is $0 because the $200,000 threshold is not reached.
- Local occupational tax is $0 because the entered local rate is 0%.
Total bonus withholding is $1,682.50. The calculator therefore returns an estimated bonus take-home of $3,317.50 and an effective withholding rate of 33.65%. If a local rate were entered, that withholding would also reduce the bonus take-home.
Gross-up mode uses the same withholding calculations in reverse. The code repeatedly tests gross bonus amounts until it finds one that produces at least the requested net amount. It then rounds the required gross bonus upward to the nearest cent.
How to Use the Kentucky Bonus Calculator: Step by Step
- Choose estimate mode to start with a gross bonus, or select gross-up mode to enter your desired take-home bonus.
- Enter the bonus amount. The calculator requires a value greater than zero.
- Select the federal withholding method and Kentucky withholding method. Each offers a flat or aggregate option.
- Enter your base annual salary and choose weekly, biweekly, semimonthly, or monthly pay frequency.
- Select your federal filing status and enter any applicable W-4 Step 2, Step 3, Step 4(a), Step 4(b), and Step 4(c) amounts.
- Enter your Kentucky standard deduction. The calculator starts with $3,270 after a reset.
- Enter a local occupational tax rate as a percentage if one applies. Enter 0 when you do not want local occupational withholding included.
- Add any extra Kentucky withholding per regular paycheck.
- Enter pre-tax and post-tax deductions that apply to each regular paycheck.
- Add optional year-to-date Social Security wages, Medicare wages, federal supplemental wages, pay periods received, and federal and Kentucky income tax already withheld.
- Check the acknowledgment confirming that the calculation is only an estimate, then calculate the result.
The main output is the estimated bonus take-home after all withholding included by the tool. Review the breakdown to see how much is assigned to federal tax, Kentucky tax, payroll taxes, and local occupational tax. The full-pay-period section combines your regular wages and bonus, while the annual snapshot provides additional planning estimates.
Factors That Can Affect Your Kentucky Bonus Calculator Result
Flat and Aggregate Methods Can Produce Different Results
The flat methods apply fixed withholding percentages to the bonus. Federal flat withholding uses 22% below the programmed supplemental-wage threshold, while Kentucky flat withholding uses 4%. Aggregate calculations instead measure how much withholding increases after the bonus is added to the regular paycheck.
| Calculator Setting | Value Used by Code |
|---|---|
| Federal flat supplemental rate | 22% up to the programmed $1,000,000 cumulative threshold |
| Federal supplemental rate above threshold | 37% |
| Kentucky flat income tax rate | 4.0% |
| Default Kentucky standard deduction | $3,270 |
| Social Security rate | 6.2% |
| Social Security wage base | $176,100 |
| Medicare rate | 1.45% |
| Additional Medicare rate | 0.9% above the programmed $200,000 threshold |
Local Occupational Tax Is User-Entered
The calculator does not select a Kentucky city or county for you. Instead, it provides one Local Occupational Tax Rate field. Whatever percentage you enter is applied to the full bonus. For regular wages, the same rate is applied to regular Kentucky taxable wages after the calculator's pre-tax paycheck deduction.
The annual snapshot also displays estimated annual local occupational tax. However, the calculator's projected annual income tax withholding and projected refund or amount due use only federal and Kentucky income taxes. Local occupational tax is not included in that projected filing difference.
Pre-Tax and Post-Tax Deductions Work Differently
The calculator subtracts pre-tax deductions from regular wages before computing federal and Kentucky taxable regular pay. Those deductions do not reduce the regular Social Security or Medicare wages in the code. Post-tax deductions do not reduce taxes. They only reduce the displayed net take-home pay for the full pay period.
If either deduction exceeds regular gross pay for one period, the code limits that deduction to the regular gross amount. The bonus itself is not reduced by these regular-paycheck deduction fields before the bonus tax calculations.
Year-to-Date Wages Matter Near Payroll Thresholds
Prior Social Security wages determine how much room remains below the $176,100 wage base. Prior Medicare wages affect the Additional Medicare calculation. Prior federal supplemental wages determine how much of the bonus can use the 22% federal flat rate before the programmed $1,000,000 threshold is crossed.
The pay periods already received and year-to-date federal and Kentucky income tax withheld are used for the annual projection. If the entered pay periods exceed the selected annual frequency, the calculator treats the number of remaining periods as zero.
All results are estimates based on the 2025 federal and Kentucky rules coded into this calculator. Actual payroll and tax results may vary because of employer procedures, local tax rules, other income, deductions, credits, tax-law changes, and information not entered here. The results are not tax, payroll, financial, or legal advice.
Frequently Asked Questions
How much tax is withheld from a bonus in Kentucky?
The amount depends on your selected methods and payroll information. Under the calculator's flat settings, it generally applies 22% federal withholding, 4% Kentucky withholding, up to 6.2% Social Security, and 1.45% Medicare. Additional Medicare and an entered local occupational tax may also reduce the bonus.
What is the Kentucky bonus withholding rate?
The calculator uses a 4.0% Kentucky withholding rate for a separately paid bonus under the flat method. For example, a $5,000 bonus produces $200 of Kentucky withholding with that method. The aggregate option instead calculates the difference between combined-pay Kentucky withholding and regular-pay withholding.
Does the Kentucky bonus calculator include local taxes?
Yes, but only when you enter a local occupational tax rate. The calculator applies that percentage to the gross bonus and also calculates local tax on regular taxable wages. It does not automatically identify a city, county, jurisdiction, rate, wage cap, exemption, or other local tax rule.
What is the difference between flat and aggregate bonus withholding?
The flat method applies a stated percentage directly to the bonus. The aggregate method adds the bonus to regular taxable wages and calculates withholding on the combined paycheck. The calculator then subtracts regular-only withholding. The difference is shown as the withholding assigned to the bonus.
Is the 22% federal bonus rate my final federal tax rate?
No. The calculator treats 22% as a federal supplemental withholding method rather than a final tax rate. Its annual federal estimate separately uses the programmed 2025 tax brackets, your filing status, the coded standard deduction, W-4 settings, dependent credits, and applicable regular-pay pre-tax deductions.
How does the Kentucky bonus gross-up calculator work?
Gross-up mode starts with the after-withholding bonus you want to receive. The calculator repeatedly tests different gross amounts using the same federal, Kentucky, payroll, and local withholding rules. It finds a gross bonus that reaches at least your target and rounds that required gross amount upward to the nearest cent.
How accurate is the Kentucky Bonus Calculator?
The calculator provides an estimate based on its programmed 2025 formulas and the values you enter. Accuracy can be affected by incomplete year-to-date information, employer payroll procedures, local occupational tax rules, other income, deductions, credits, or circumstances the calculator does not model. Final tax liability is determined separately.