Bonus Tax Calculator
Choose how your employer withholds on the bonus, or gross up a target. The calculator applies the IRS supplemental wage rules, Social Security, Medicare and a flat state rate.
Net Bonus
$3,267.50
Gross Bonus
$5,000.00
Federal Income Tax Withheld
$1,100.00
Social Security
$310.00
Medicare
$72.50
State and Local Tax
$250.00
Total Withheld
$1,732.50
Withheld as a Share of the Bonus
34.65%
How it works
A bonus is a supplemental wage, and IRS Publication 15 lets employers withhold federal income tax on it in two ways. The flat-rate (percentage) method takes a flat 22%. Once an employee's supplemental wages for the year pass $1,000,000, the excess must be withheld at 37%, whichever method was used for the rest.
The aggregate method adds the bonus to a regular paycheck and withholds as if the total were one paycheck, then subtracts what the regular paycheck alone would have had withheld. Because the combined paycheck is annualized, a large bonus can be withheld at a higher rate than you will actually pay; the difference comes back when you file. The aggregate method is required when the bonus is paid with regular wages without the two amounts being specified, and when no income tax was withheld from your regular wages this year or last year (Publication 15, section 7).
Social Security (6.2%) applies until your year-to-date wages from this employer reach the wage base ($184,500 in 2026), and Medicare (1.45%) applies to all of it, plus 0.9% on wages over $200,000 for the year. That is why the calculator asks what you have already been paid this year. State tax is the flat rate you enter.
The gross-up option works backwards: it finds the bonus that leaves the target after flat-rate withholding. Within one tax band that is the target divided by (1 − total rate); the calculator also handles a bonus that crosses the wage base or another threshold.
Formula
flat-rate federal = flat rate × bonus up to $1,000,000 YTD + 37% × the rest aggregate federal = W(regular pay + bonus) − W(regular pay) W(pay) = bracket tax on max(0, pay × paychecks − withholding standard deduction) ÷ paychecks Social Security = 6.2% × the part of the bonus below the wage base after YTD wages Medicare = 1.45% × bonus + 0.9% × the part above $200,000 YTD state = state rate × bonus net bonus = bonus − federal − Social Security − Medicare − state gross-up = target net ÷ (1 − total rate), within one band
Example
A $5,000 bonus in 2026 with $50,000 already paid this year, by the flat-rate method: federal $1,100 (22%), Social Security $310, Medicare $72.50 and a 5% state rate $250, for a net bonus of $3,267.50, 34.65% withheld.
To net $5,000 instead, the bonus has to be $5,000 ÷ (1 − 0.3465) = $7,651.11.
IRS Publication 15 (2026), Example 4: a single employee paid $2,000 a month gets a $1,000 bonus and then a $2,000 bonus. By the aggregate method, the second bonus is withheld on $5,000 less what was withheld on $3,000: $418.33 − $178.33 = $240.00, the $240 the IRS shows.
Assumptions and limitations
- This is an estimate for planning. It is for informational and educational purposes and is not financial, tax or legal advice.
- Withholding is not the tax you owe. A bonus is taxed as ordinary income on your return along with your other pay; if 22% is more or less than your actual rate, the difference shows up in your refund or balance due.
- The aggregate method follows the Publication 15-T percentage method for a 2020 or later Form W-4 with Steps 2 to 4 blank, combining the bonus with a regular paycheck paid at the same time. Employers using the wage bracket tables round to whole dollars, so their figure can differ by about a dollar.
- No 401(k) or other pre-tax deduction is taken from the bonus. If your plan defers a percentage of bonuses, the federal and state tax on the bonus fall by that share times the rate.
- Social Security and Medicare depend on wages already paid by this employer this year. A new employer starts the wage base over; excess Social Security from two employers is refunded on your return.
- State tax is one flat rate on the whole bonus. Many states have their own supplemental rate or withhold on bonuses differently.
- The flat rate defaults to 22%, the only rate Publication 15 allows for the optional flat-rate method in 2025 and 2026. The 37% rate on supplemental wages over $1,000,000 is mandatory and is applied automatically.
Frequently asked questions
Why was my bonus taxed so much more than my paycheck?
Usually it was not taxed more, only withheld more. Under the aggregate method a bonus added to one paycheck looks like a much higher annual salary, so it is withheld at a higher bracket. Under the flat-rate method it is 22% regardless of your bracket. Either way your actual tax is settled on your return, where the bonus is ordinary income like the rest of your pay.
Which method will my employer use?
Publication 15 (section 7) sets the rules. A bonus paid in the same check as regular wages without the two amounts being specified must use the aggregate method. A bonus identified separately can use either method, provided income tax was withheld from your regular wages this year or last year; if none was, the employer must use the aggregate method. Otherwise the choice is the employer's, and your pay stub usually shows which one was used.
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