Federal Withholding Calculator
Estimate federal income tax withholding using IRS Pub 15-T percentage method with W-4 inputs for filing status and adjustments.
Bonus Tax Calculator
Calculate taxes on bonus pay using the flat 22% federal rate (37% over $1M) or aggregate method. Includes state supplemental wage tax estimates.
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$
%
Federal Tax⧉
$2,200.00
Flat 22% method
State Tax⧉
$500.00
Social Security⧉
$620.00
Medicare⧉
$145.00
Total Tax Withheld⧉
$3,465.00
34.7% effective rate
Net Bonus⧉
$6,535.00
Planning notes, formulas, and examples
About the Bonus Tax Calculator
Bonuses and other supplemental wages are subject to special federal tax withholding rules. Employers can choose between two IRS-approved methods: the flat percentage method, which withholds 22% on the first $1 million and 37% on amounts exceeding $1 million, or the aggregate method, which combines the bonus with regular pay and calculates withholding on the total as if it were a single payment.
The method chosen significantly affects how much tax is withheld from the bonus check. The flat method is simpler and often preferred for its predictability, while the aggregate method may withhold more or less depending on the employee's regular pay and tax bracket. Neither method changes the total tax owed—the difference is reconciled when filing the annual tax return.
This Bonus Tax Calculator estimates the net bonus under both methods. Enter your bonus amount, regular pay, filing status, and state supplemental rate to compare take-home amounts. Whether you're an employee planning how to spend a year-end bonus or an HR professional choosing the withholding method, this estimate gives you the clarity you need.
When This Page Helps
Employees often experience sticker shock when they see how much tax is withheld from a bonus. This calculator shows estimated withholding under both IRS methods, plus state and FICA taxes. Understanding the breakdown helps employees plan accurately and reduces confusion about why bonus checks look smaller than expected.
How to Use the Inputs
- Enter your bonus amount.
- Select the withholding method: Flat Rate or Aggregate.
- For the aggregate method, enter your regular per-period gross pay and filing status.
- Enter your state supplemental wage tax rate (or 0 if your state has none).
- Review federal tax, state tax, FICA, and net bonus amounts.
- Compare both methods to understand the withholding difference.
Formula used
Flat Method: Federal Tax = Bonus × 22% (37% on amounts over $1,000,000)
FICA = Bonus × 7.65% (subject to wage base limits)
State Tax = Bonus × State Supplemental Rate
Net Bonus = Bonus − Federal Tax − State Tax − FICAExample Calculation
Result: $6,535 net bonus
Federal flat rate: $10,000 × 22% = $2,200. State: $10,000 × 5% = $500. Social Security: $10,000 × 6.2% = $620. Medicare: $10,000 × 1.45% = $145. Total tax: $3,465. Net bonus: $10,000 − $3,465 = $6,535.
Tips & Best Practices
- The 22% flat rate is a withholding rate, not your actual tax rate—you may owe more or get a refund when filing.
- Bonuses over $1,000,000 in a calendar year are withheld at 37% on the excess above $1M.
- The aggregate method may over-withhold if the combined amount pushes you into a higher bracket temporarily.
- Consider increasing 401(k) contributions on bonus pay to reduce taxable income.
- FICA taxes (Social Security and Medicare) apply to bonuses just like regular pay.
- Nine states have no income tax and won't withhold state tax on bonuses.
- If you've already hit the Social Security wage base for the year, no additional SS tax applies to the bonus.
Flat Method vs. Aggregate Method in Detail
Most payroll software defaults to the flat method for simplicity. The employer withholds exactly 22% in federal tax (plus FICA and state), making the calculation straightforward. The aggregate method is more complex: it temporarily adds the bonus to a prior regular paycheck, calculates total withholding using standard tax tables, then subtracts the already-withheld amount on regular pay.
Year-End True-Up
Regardless of which withholding method the employer uses, the employee's actual tax liability is determined on their annual tax return. If too much was withheld (common with the aggregate method), the employee receives a refund. If too little was withheld, additional tax is owed. Adjust W-4 allowances proactively if you expect a large bonus.
Maximizing Net Bonus
Strategies to increase the net bonus include maximizing pre-tax 401(k) contributions, making HSA contributions, and timing the bonus payment to a period where you've already exceeded the Social Security wage base. Consult with a tax advisor to align bonus timing with your overall tax strategy.
Sources & Methodology
Last updated:
Frequently Asked Questions
The IRS flat rate for supplemental wage withholding is 22% on the first $1 million in bonus/supplemental wages per calendar year. Any amount exceeding $1 million is withheld at 37%, the top marginal rate.
The aggregate method combines the bonus with a prior regular payroll amount and calculates federal withholding on the total as if it were a single regular payment. It then subtracts what was already withheld on the regular pay to determine the bonus withholding. This can result in higher or lower withholding than the flat method.
Neither method changes total tax liability—both affect only the timing of tax payments. The flat method provides predictable withholding. The aggregate method may over-withhold for lower earners but more closely approximates actual tax for high earners. The difference resolves when filing your annual return.
Bonuses are taxed at the same rates as regular income on your annual return. The difference is in withholding: bonuses can use the flat 22% rate or aggregate method, while regular pay uses standard W-4-based withholding tables. Final tax liability is identical regardless of withholding method.
Yes. Social Security tax (6.2%) applies to bonuses up to the annual wage base limit for the payroll year. Medicare (1.45%) applies to all bonus amounts. The additional 0.9% Medicare surtax applies if total wages exceed the applicable threshold.
If your year-to-date wages already exceed the Social Security wage base, no additional Social Security tax (6.2%) is withheld from the bonus. Medicare (1.45%) continues to apply with no cap. This increases your net bonus for bonuses paid late in the year.
Most states with income tax apply a supplemental wage rate to bonuses. Rates vary: California uses standard withholding tables, New York applies 11.7%, and others use flat supplemental rates. Nine states have no income tax.
Yes. If your employer allows it, you can elect to contribute part or all of a bonus to your pre-tax 401(k), reducing taxable income for the year of contribution. The contribution still has to fit within the annual 401(k) limits that apply to your payroll year.
More in this topic
Local Tax Calculator
Calculate local income tax withholding by applying your municipality's tax rate to taxable wages for cities and counties.
State Withholding Calculator
Estimate state income tax withholding based on wages, filing status, and state-specific tax rates for all 50 U.S. states.