A bonus is exciting until payday, when a surprisingly small check arrives. Most people ask the same question: "How much will I actually take home?" This bonus calculator from Smekys estimates your gross bonus, the federal tax withheld on it, and the real after-tax amount you can expect in your bank account. It handles both common bonus structures — a percentage of your salary and a fixed flat dollar amount — and applies the US supplemental wage withholding rules the way most payroll systems actually use them.
Adjust the sliders and the result card updates instantly. Compare a percentage bonus against a flat one, test different tax-withholding rates, and see exactly how a bonus changes your total annual compensation.
How to Use
- Enter your Annual Base Salary — your gross yearly pay before any bonus, as shown on your offer letter or most recent pay stub.
- Set the Bonus Type. Choose percentage when your bonus is quoted as a share of salary (for example, "10% annual bonus"). Choose flat when you were promised a fixed dollar amount (for example, a $5,000 year-end bonus).
- Fill in the Bonus Percentage if you picked percentage mode. Enter the number your employer quoted; 5%–15% is typical for performance bonuses.
- Fill in the Flat Bonus Amount if you picked flat mode. This is the gross dollar figure your company promised before taxes.
- Set the Bonus Tax Withholding rate. The default is 22%, the flat supplemental wage rate the IRS applies to bonuses under $1 million. Change it if your payroll uses your actual marginal rate, or use 37% for a very large bonus above the $1 million threshold.
- Read the result card: Gross Bonus is the total before tax, Federal Tax Withheld is taken out immediately, and Net Bonus (Take-Home) is what actually lands in your account. The card also shows your effective bonus as a percentage of salary and your total annual compensation.
How Bonuses Are Taxed in the US
The key thing most people miss is that a bonus is treated as supplemental wages, not ordinary salary. Under IRS rules in Publication 15, employers may withhold federal income tax on supplemental wages using the percentage method: a flat 22% rate on the payment, up to $1 million in a calendar year. Any portion of supplemental wages above $1 million in the same year is withheld at 37%.
This is why a $10,000 bonus often arrives closer to $7,800 on the pay stub. The 22% is only a withholding amount, not your final tax bill. When you file your return, the bonus is added to your other income and taxed at your real marginal rate. If your actual bracket is lower than 22%, you may get some of that withholding back as a refund; if it is higher, you may owe a little more in April.
The math itself is straightforward:
- Percentage bonus: gross = annual salary × bonus percentage ÷ 100.
- Flat bonus: gross = the fixed dollar amount.
- Tax withheld: gross bonus × withholding rate ÷ 100.
- Net bonus: gross bonus − tax withheld.
For example, on an $80,000 salary with a 10% bonus, the gross bonus is $8,000. At the 22% supplemental rate, $1,760 is withheld, leaving a net bonus of $6,240. Switch the bonus type to a flat $5,000 and the net drops to $3,900 after $1,100 in withholding.
Percentage Bonus vs Flat Bonus
The two structures look similar on paper but behave differently over time. A percentage bonus scales with your salary, so every raise automatically grows your bonus, and it is easy to compare offers across companies. A flat bonus is simpler and more predictable, but it does not grow unless your employer explicitly raises the dollar amount.
If you are negotiating, ask whether the bonus is a percentage of base salary or a fixed figure. A "10% bonus" on a $90,000 salary is worth $9,000 this year and grows as you advance. A "$7,500 flat bonus" is guaranteed but stays flat year after year unless renegotiated. This calculator lets you enter both side by side to see which one puts more money in your pocket after tax.
Examples
Example 1 — A standard performance bonus. An employee earns an $80,000 base salary and is promised a 10% annual bonus. Gross bonus is $8,000. With 22% supplemental withholding, $1,760 goes to federal tax and the net take-home bonus is $6,240. Total annual compensation rises to $88,000.
Example 2 — A flat year-end bonus. The same employee is instead offered a flat $5,000 holiday bonus. Gross bonus is $5,000. Withholding at 22% is $1,100, so the net bonus is $3,900, and total compensation is $85,000. Switching back to the percentage mode shows the percentage bonus is worth $2,340 more after tax.
Example 3 — A large executive bonus. A senior employee earns a $1,000,000 salary and a 15% bonus. Gross bonus is $150,000. Because the total supplemental payment crosses high earnings, a 37% withholding rate is modeled: $55,500 is withheld and the net bonus is $94,500, bringing total compensation to $1,150,000.
FAQ
How much will my bonus be taxed?
Most US bonuses are withheld at a flat 22% federal supplemental wage rate. On a $10,000 bonus that is $2,200 withheld, leaving about $7,800. Bonuses above $1 million in a single calendar year are withheld at 37%. This is withholding, not your final tax — you settle the difference when you file your return.
Is a bonus calculated on base salary or total salary?
A percentage bonus is almost always calculated on your base salary, before overtime, commissions, or other bonuses. If your offer says "10% bonus," confirm whether that means 10% of base or 10% of total cash compensation, because the two numbers can differ significantly.
Why is my bonus check smaller than I expected?
Because employers withhold federal income tax (22% flat on supplemental wages), plus Social Security, Medicare, and any state tax, before the money reaches you. The 22% federal withholding alone can feel steep, and it is common to see a bonus reduced by 30%–40% once every deduction is applied.
Should I choose a percentage or a flat bonus?
A percentage bonus grows with your salary and is easier to compare across companies; a flat bonus is fixed and predictable. If you expect raises or promotions, a percentage bonus usually wins over time. If you want certainty and a guaranteed number on your offer letter, a flat bonus may feel safer.
Will I get money back when I file my taxes?
Possibly. If your actual marginal tax rate is below the 22% flat withholding rate, you may receive some of the withheld amount as a refund. If your real rate is higher, you may owe additional tax. The bonus is simply added to your annual income and taxed at your true bracket at filing time.
Does a 401(k) or retirement contribution affect my bonus?
It can. If you direct part of your bonus to a traditional 401(k), that portion is pre-tax and reduces the taxable bonus in the year you receive it. Many employees ask payroll to split the bonus so retirement contributions come out first, which lowers both the immediate tax hit and their current taxable income.
Disclaimer
This bonus calculator is provided for informational purposes only and does not constitute tax, payroll, or financial advice. Withholding estimates use the US supplemental wage percentage method (22%, or 37% above $1 million) and do not include Social Security, Medicare, state, or local taxes, which vary by location and circumstance. Actual net pay depends on your employer's payroll method, your W-4 elections, filing status, and total annual income. Always confirm your bonus withholding and final tax position with a qualified tax professional or your payroll department.