A bonus tax calculator shows you exactly how much federal, state, and FICA tax will be withheld from your bonus — before you receive it. Because the IRS classifies bonuses as supplemental wages, employers can withhold using either the 22% flat rate or the aggregate method, each producing a different take-home amount. Enter your details below to see both estimates instantly.
Bonus Details
Flat Rate Method
22% federal supplemental rate
Aggregate Method
Bonus taxed as ordinary income
Method Comparison Summary
How to Use the Bonus Tax Calculator
Understanding how much tax is withheld from your bonus helps you plan your finances, decide whether to adjust your W-4, or contribute more to your 401k to reduce the taxable amount. The IRS treats bonuses as supplemental wages, which means they are taxed differently from your regular paycheck — and your employer has two approved methods for calculating that withholding.
Step 1: Enter Your Bonus Amount
Type the gross bonus amount before any taxes or deductions. This is the number on your bonus letter or what your employer told you you would receive. If you are expecting a $10,000 year-end bonus, enter 10000. The calculator works for any bonus size from a few hundred dollars to six figures.
Step 2: Select Your Filing Status and State
Your filing status (Single, Married Filing Jointly, Head of Household, etc.) affects the aggregate method calculation because it determines which federal tax brackets apply to your total income. Your state selection applies a simplified state income tax rate — this matters because most states with an income tax also withhold from bonuses. States like Texas, Florida, and Washington have no state income tax, so those fields will show $0.
Step 3: Enter Your Annual Salary
The aggregate method calculation requires your regular annual salary because it combines your bonus with your annualized paycheck to determine the appropriate marginal tax rate. The flat rate method ignores your salary entirely — it uses 22% regardless of income level (up to $1 million). If you are primarily curious about the flat rate, the salary field does not change that result, but it is needed for an accurate aggregate comparison.
Understanding the Flat Rate Method
The flat rate method is the most common approach. The IRS sets the supplemental wage withholding rate at 22% for bonuses up to $1 million (37% above $1 million). Your employer applies this rate to the full bonus amount regardless of your total income or marginal bracket. Because the flat rate is fixed, it is easy to calculate: a $5,000 bonus results in $1,100 of federal withholding every time, no matter what else you earned that year. FICA taxes (Social Security and Medicare) and state taxes are added on top.
Understanding the Aggregate Method
The aggregate method is more precise but more complex. Your employer combines your bonus with your most recent regular paycheck, annualizes that combined figure, and calculates withholding as if you would earn that amount all year. The bonus withholding is then the difference between the withholding on that combined figure and what was already withheld from your regular paycheck. For higher earners, this method often results in more federal withholding than the 22% flat rate because the bonus pushes their annualized income into a higher bracket. For lower earners, the aggregate method might actually result in less withholding.
What Happens at Tax Filing Time
Both withholding methods are just estimates. When you file your annual tax return, the IRS reconciles your total tax liability against everything withheld throughout the year. If the flat rate 22% exceeded your actual effective rate, you receive a refund for the overpayment. If your actual rate was higher (common for high earners), you may owe additional tax. The aggregate method tends to produce a closer estimate to your actual liability because it accounts for your total income level.
FAQ
Is this bonus tax calculator free?
Yes, completely free with no signup, no account, and no limits. All calculations run entirely in your browser using JavaScript — nothing is sent to any server, so your salary and bonus information stays completely private on your device.
Is my salary and bonus information private?
Absolutely. This tool runs 100% client-side in your browser. No figures you enter are ever transmitted over the internet or stored anywhere. You can disconnect from the internet after the page loads and the calculator will still work perfectly.
What is the federal bonus tax rate?
The IRS treats bonuses as supplemental wages. Under the flat rate method, the federal withholding rate is 22% for bonuses up to $1 million, and 37% for amounts above $1 million. This is the rate most employers use because it is simple and requires no payroll adjustment. It does not represent your true tax owed — the difference is reconciled when you file your return.
What is the aggregate method for bonus taxes?
The aggregate method adds your bonus to your most recent regular paycheck and calculates withholding as if you earned that combined amount all year. The resulting withholding rate depends on your total annualized income and filing status. This method often results in higher withholding than the flat rate method, especially for higher earners, but it more closely mirrors what you will actually owe.
Does my employer choose the flat rate or aggregate method?
Yes, your employer selects the withholding method — employees cannot choose. Most employers use the flat rate method because it is simpler to administer. Some payroll systems default to the aggregate method. This calculator shows your estimated take-home bonus under both methods so you know what to expect regardless of which your employer uses.
Will I owe more taxes on my bonus at filing time?
Possibly. Withholding is only an estimate. If your effective tax rate for the year turns out to be higher than the 22% flat withholding rate, you may owe additional tax when you file. Conversely, if 22% exceeds your effective rate, you will receive a refund for the over-withheld amount. The aggregate method generally produces a more accurate withholding estimate.
Are Social Security and Medicare taxes taken out of bonuses?
Yes. FICA taxes apply to bonuses just like regular wages. Social Security tax is 6.2% on earnings up to the annual wage base ($176,100 for 2025), and Medicare is 1.45% with no cap. If your regular salary has already exceeded the Social Security wage base, no additional Social Security tax is withheld from your bonus.
How does state tax affect my bonus?
Most states that have an income tax also withhold state taxes from bonuses. Some states use the same supplemental flat rate as the federal government, while others apply their own flat rate or use the aggregate method. This calculator includes simplified state tax rates for the 10 most-populated US states. Your actual state withholding may vary based on your specific state's rules and your W-4 elections.