Missouri Bonus Calculator
Bonus Details
Federal W-4 Settings
Missouri Withholding (Form MO W-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.
- Missouri has a flat 4.7 percent withholding rate for separately paid bonuses. This is different from the regular progressive brackets (0 percent to 4.7 percent).
- The aggregate method combines your bonus with regular wages and applies your standard deduction. The bonus portion equals the difference between combined withholding and regular-only withholding.
- Kansas City and St. Louis levy a 1 percent local earnings tax on wages earned by residents and workers within city limits.
- 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 Missouri Bonus Calculator?
The Missouri Bonus Calculator is a tool for estimating bonus take-home pay or working backward from a net bonus target. It calculates federal and Missouri income tax withholding, Social Security, Medicare, Additional Medicare, and user-entered local earnings tax. The results show estimated bonus deductions and the amount left after withholding.
Gross means pay before withholding. For the bonus result, net means the amount left after modeled taxes. In gross-up mode, the tool estimates the gross bonus required for your chosen net amount.
Prior year-to-date (YTD) figures cover wages and withholding before the payment being modeled.
Results also include an effective withholding rate, alternative federal and Missouri withholding amounts, full-period net pay, and an annual snapshot. The snapshot shows salary plus this bonus, a federal marginal bracket, annual income-tax estimates, projected withholding, and a possible refund or balance due.
How the Bonus Withholding Formula Works
The calculator subtracts six withholding amounts from the gross bonus:
B is the gross bonus; N is bonus take-home. F is federal withholding, S is Social Security, and M is Medicare. A is Additional Medicare, Q is Missouri withholding, and L is local earnings tax.
Supplemental wages are extra payments such as bonuses. Flat federal mode applies 22% within its $1 million supplemental-wage threshold and 37% above it. Prior supplemental wages determine the remaining room. Flat Missouri mode applies 4.7%. Local withholding equals the bonus multiplied by your entered percentage divided by 100.
Aggregate mode uses this difference for either federal or Missouri withholding:
T is bonus withholding for the selected tax. R is regular gross pay minus the allowed pre-tax deduction. H multiplies check wages by yearly pay periods, applies stored deductions, tax brackets, and adjustments, then calculates withholding for one check.
Missouri aggregate calculations subtract the selected state standard deduction before applying the stored tax schedule. Its zero-tax band extends through $1,313 of taxable income. Higher bands use rates from 2% to 4.7%.
Social Security uses 6.2%, subject to the stored $176,100 wage base. Regular wages use available room first. Medicare is 1.45%; bonus Additional Medicare uses 0.9% on incremental wages above the stored $200,000 threshold.
Prior YTD Social Security Wages and Prior YTD Medicare Wages affect how much of the bonus crosses those limits.
Example: a $5,000 bonus with 1% local withholding
Enter a $5,000 bonus, $75,000 salary, biweekly pay, and flat methods. Choose federal Married Filing Jointly and Missouri Married (Spouse Works or Filing Separate). Enter 1% local tax. Leave other amounts at zero and Step 2 unchecked.
| Withholding item | Calculation | Amount |
|---|---|---|
| Federal income tax | $5,000 × 22% | $1,100.00 |
| Missouri income tax | $5,000 × 4.7% | $235.00 |
| Social Security | $5,000 × 6.2% | $310.00 |
| Medicare | $5,000 × 1.45% | $72.50 |
| Additional Medicare | Threshold not reached | $0.00 |
| Local earnings tax | $5,000 × 1% | $50.00 |
Add the six amounts to get $1,767.50 withheld. Subtract that from $5,000 for $3,232.50 in bonus take-home. Divide withholding by the gross bonus to get the displayed 35.35% effective withholding rate.
How to Use the Missouri Bonus Calculator: Step by Step
The $5,000 bonus and $75,000 salary hints are placeholders, not entered values. Replace them with your own figures.
- Choose Calculator Mode. Select a gross-bonus estimate or a target take-home amount.
- Enter Bonus Amount (Gross), or Desired Net Bonus (Take-Home Target) in gross-up mode.
- Set each Bonus Withholding Method. Federal and Missouri choices are independent.
- Enter Base Annual Salary (Regular Pay), excluding this bonus.
- Select Pay Frequency: weekly (52), biweekly (26), semimonthly (24), or monthly (12) checks.
- Choose Federal Filing Status: Single, Married Filing Jointly, or Head of Household.
- Complete Federal W-4 Settings. Steps 3, 4(a), and 4(b) are annual amounts; Step 4(c) is per check.
- Complete Missouri Withholding (Form MO W-4). Choose Missouri Filing Status and enter Local Earnings Tax Rate and Extra Missouri Withholding Per Check.
- Enter Pre-Tax Deductions and Post-Tax Deductions per regular paycheck.
- Complete Year-To-Date Data. Supply prior Social Security, Medicare, and federal supplemental wages, completed pay periods, and federal and Missouri taxes already withheld.
- Check the acknowledgment that withholding differs from final tax liability.
- Click Calculate Bonus Take-Home or Calculate Required Gross Bonus, according to your mode.
Bonus Take-Home covers the bonus alone. Net Take-Home Pay This Period includes regular wages, the bonus, all modeled taxes, and both paycheck deductions.
What to Check Before Using Your Result
For a bonus budget, use Bonus Take-Home, not full-period net pay. The example’s full-period take-home is $5,576.56 because it also includes regular wages.
Filing status and withholding settings
Federal and Missouri filing statuses are separate. These are standard deductions stored in the calculator, not a current-law lookup:
| Filing-status setting | Stored annual deduction |
|---|---|
| Federal or Missouri: Single | $15,000 |
| Federal: Married Filing Jointly | $30,000 |
| Federal or Missouri: Head of Household | $22,500 |
| Missouri: Married (Spouse Works or Filing Separate) | $15,000 |
| Missouri: Married (Spouse Does Not Work) | $30,000 |
W-4 Step 2 adds a fixed $5,000 to annualized taxable wages. Step 3 dependent credits reduce modeled federal tax. Step 4(a) adds other annual income, and Step 4(b) subtracts annual deductions. Step 4(c) and extra Missouri withholding affect regular-pay withholding, not a separate bonus deduction.
Annual snapshot limits
The annual model assumes unchanged salary and regular deductions. Remaining checks equal yearly periods minus completed periods, with a minimum of zero. Completed periods are rounded down to whole numbers. Prior supplemental wages affect the flat federal threshold but are not added to modeled annual income or annual taxes.
The effective rate measures the share of your bonus withheld. The marginal bracket identifies the last dollar’s rate in the annual federal model. These figures measure different things and need not match.
The projected refund or amount due compares federal and Missouri income taxes only. It excludes local tax, Social Security, and Medicare, even though an annual local tax estimate appears separately.
Calculation limits to recognize
The full-period calculation can overstate Additional Medicare when prior wages already exceed $200,000. It counts the prior excess in regular-wage withholding. The bonus-only calculation cancels that prior excess.
The 37% supplemental override runs only in flat federal mode, not aggregate mode. The local-rate field does not reject implausibly high percentages, which can make gross-up results unreliable.
Results are estimates, not tax, payroll, or legal advice. Actual payments can differ because of tax rules, employer practices, deduction treatment, and personal details.
Frequently Asked Questions
How much of a $5,000 bonus will I take home in Missouri?
Under the example’s flat-method settings, the tool estimates $3,232.50 with a 1% local rate. Setting local tax to zero raises bonus take-home to $3,282.50. These figures assume the stated salary and filing statuses, no entered deductions, no prior wages, and no other W-4 adjustments.
What is the difference between flat and aggregate bonus withholding?
Flat mode applies stored bonus percentages. Aggregate mode calculates withholding for combined wages, then subtracts regular-only withholding. The calculator shows alternative federal and Missouri tax amounts, not alternative net-pay totals. In the example, federal aggregate withholding is $900.19 instead of $1,100.00. Missouri withholding is $235.00 under either method.
How do I calculate a bonus gross-up?
Choose gross-up mode and enter your desired net bonus. The tool repeatedly tests gross amounts using your selected withholding settings, then rounds the result upward to a cent. With the example’s 1% local rate, a $5,000 target produces $7,733.96 gross and $5,000.01 displayed take-home. Employer-side costs are not calculated.
Does the calculator include Kansas City and St. Louis earnings tax?
It includes a manual Local Earnings Tax Rate field, not a city eligibility check. Enter 1 for 1%, or 0 when modeling no local tax. The tool applies that percentage to the entire bonus and to regular wages after its pre-tax deduction. It does not determine your location or exemptions.
Do pre-tax deductions reduce all bonus taxes?
No. The pre-tax field reduces regular wages used for federal, Missouri, and local tax calculations. It does not reduce Social Security or Medicare wages. Post-tax deductions reduce full-period take-home only. Both fields apply to regular pay and are independently capped at regular gross pay. There is no bonus-specific deduction field.
Why is the Calculate button disabled?
The button needs a positive bonus or net target, a salary of zero or more, and the acknowledgment checkbox. Calculation requires at least $0.01 for the bonus field. Optional blank amounts become zero. Negative entries or amounts above $1 billion fail validation. JavaScript must initialize successfully. Reset clears entries and restores defaults.
What tax year does the Missouri Bonus Calculator use?
The calculator uses fixed settings labeled for 2025. There is no tax-year selector or automatic update. Its W-4 adjustments and annual snapshot are simplified models. Displayed dollar amounts and percentages use two decimal places. Treat the output as an estimate, not confirmation of your employer’s withholding or filing results.