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A $10,000 bonus paid on its own check nets $7,035: 22% federal income tax, 6.2% Social Security, 1.45% Medicare. Put your own figure in below — then read why a bonus check sometimes looks far worse than that.
Last updated 3 October 2026
Estimates only — not tax, payroll, or financial advice. This page models the flat-rate supplemental method and nothing else: 22% federal income tax on the bonus, 6.2% Social Security up to the $184,500 wage base, 1.45% Medicare, and whatever flat state percentage you type. It does not model the aggregate method, the 0.9% Additional Medicare Tax, the 37% rate above $1 million in supplemental wages, local tax, or anything your employer deducts for benefits. It is not a Publication 15-T withholding calculation and not a substitute for your W-4. Confirm your own figures with a qualified tax or payroll professional.
If your employer pays the bonus on a separate check and uses the flat supplemental rate, the arithmetic is fixed and you can do it on paper. Federal income tax takes 22%. Social Security takes 6.2% and Medicare takes 1.45%, exactly as on any other wages. Nothing else federal comes out. That is 29.65% gone before a single state touches it.
$10,000 bonus · flat rate · $70,000 in wages so far this year · no state income tax
All three rates are from IRS Publication 15 (Circular E) for 2026. Add state income tax and the net falls further: a flat 5% on the same bonus takes another $500 and leaves $6,535.
This is the part nearly every bonus page skips. Your employer may use the flat 22% only if it withheld income tax from your regular wages in the current or the immediately preceding calendar year. Publication 15 states the condition before it states the rate:
“If you withheld income tax from an employee's regular wages in the current or immediately preceding calendar year, you can use one of the following methods for the supplemental wages. a. Withhold a flat 22% (no other percentage allowed).”
When that condition is not met, the flat rate is not an option your employer declined. It is gone: “If you didn't withhold income tax from the employee's regular wages in the current or immediately preceding calendar year, use method 1b.” Method 1b is the aggregate method, and in that case it is mandatory.
The condition turns on whether income tax actually came out, so it fails whenever none did. A first payroll of the year that is the bonus, or regular pay low enough that no federal income tax was withheld, both land there.
The aggregate method uses no rate at all. Publication 15 describes it as adding the supplemental wages to the regular wages paid at the same time, then “withhold federal income tax as if the total were a single payment for a regular payroll period”, then “Subtract the tax already withheld or to be withheld from the regular wages. Withhold the remaining tax from the supplemental wages.”
Read that last step again. Everything the combined amount pulls above what your normal pay would have pulled comes out of the bonus.
Say you are paid $2,000 every two weeks and the bonus is $10,000. Your employer treats that one check as $12,000 of ordinary pay. The Publication 15-T tables work per pay period, so a $12,000 biweekly check is handled as though you earned $12,000 every two weeks all year, around $312,000 annualized. Federal rates rise with income, so the tables charge that check at a rate your actual salary never reaches. The withholding on your usual $2,000 is subtracted, and the whole remainder is taken from the bonus.
That is the mechanism behind every “they took 40% of my bonus” story. Nothing went wrong, and your tax did not go up.
Everything above is withholding: money your employer sends in on your behalf during the year. It is not what you owe. What you owe is worked out on your return, against your whole year, and the withholding is credited against it.
So an over-withheld bonus is not lost. Publication 505 is blunt about where it goes: “Your employer can't repay any of the tax previously withheld. Instead, claim the full amount withheld when you file your tax return.” The IRS states both failure modes in one line: “Too little can lead to a tax bill or penalty. Too much can mean you won't have use of the money until you receive a tax refund.” (IRS, Tax withholding)
Which means the flat 22% is not automatically the good outcome. If your top marginal rate is above 22%, a flat-rate bonus has less taken out than that bonus will eventually cost you, and the gap arrives with your return: “If not enough tax is withheld, you will owe tax at the end of the year and may have to pay interest and a penalty.” The aggregate method's bigger bite is often closer to what you actually owe.
Two of the deductions above do not settle up that way. The 22%, or the aggregate figure, is income tax withholding. The 6.2% and the 1.45% are separate taxes, and Publication 15 says supplemental wages are subject to them “regardless of the method you use to withhold income tax”.
Publication 15 gives the rate as 22% “(37% if supplemental wages paid to an employee during the calendar year exceed $1 million)”. It is a running calendar-year total of your supplemental wages from that employer, not a test on one payment, so several large bonuses can cross it between them. This page does not model it.
Social Security is 6.2% on wages up to a wage base limit, which Publication 15 puts at $184,500 for 2026. Once your wages for the year pass it, that 6.2% stops. Same bonus, different month, different net: with $190,000 already earned — past the wage base, and not yet past the $200,000 where the 0.9% starts — the $10,000 bonus above loses its $620 Social Security line entirely and nets $7,655 instead of $7,035. That is what the year-to-date wages field on this page is for, and it is the one input here most people leave empty when it would change their answer.
On top of the 1.45% there is an Additional Medicare Tax of 0.9%. Your employer must withhold it once wages paid to you for the year exceed $200,000, and that employer threshold does not change with your filing status. Yours does: $250,000 married filing jointly, $125,000 married filing separately, $200,000 for everyone else (IRS Topic no. 560).
The two can therefore disagree in both directions. A couple filing jointly can have the 0.9% withheld from a bonus at $200,000 of wages and settle it on the return. Someone married filing separately passes their own $125,000 threshold long before any employer starts withholding. This page does not model the 0.9% on the bonus view.
Take the bonus stub and divide the federal income tax line by the gross bonus. Exactly 22% means the flat supplemental rate. Anything else means the bonus was aggregated with regular wages, or paid inside a regular check, which comes to the same thing.
Then look at the Social Security line. 6.2% of the bonus means you were under the wage base through that whole check. Less than that, or zero, means you crossed $184,500 during it.
State and local income tax. Out of scope here, and nothing on this page is sourced for any state. The state field applies a flat percentage you type to the bonus, which is only as right as the figure you put in it.
Anything your employer deducts for benefits. If 401(k), HSA or insurance comes out of the bonus as well, your real net is lower than this page shows.
Your W-4 and the withholding tables. The flat supplemental rate ignores your W-4 entirely; the aggregate method does not. Modeling the second needs the Publication 15-T tables, which this page deliberately does not attempt.
Rates on this page were read against the 2026 IRS sources above on 1 October 2026. Nothing you type leaves your browser. More: the rest of the PaystubKit calculators.
If your employer pays the bonus separately and uses the flat supplemental rate, 29.65% comes out before any state tax: 22% federal income tax, 6.2% Social Security and 1.45% Medicare. On a $10,000 bonus that is $2,965 withheld and $7,035 in your account. If your employer uses the aggregate method instead, the federal share can be much larger.
Almost always the aggregate method. Your bonus was added to the regular wages paid at the same time and withheld on as if that combined amount were one ordinary pay period, then the withholding on your regular wages was subtracted and the entire remainder came out of the bonus. Because federal rates rise with income, one inflated pay period is handled at a rate your real salary never reaches. More was withheld, not more tax owed.
Only on a condition almost no calculator mentions. Publication 15 allows it if the employer withheld income tax from your regular wages in the current or immediately preceding calendar year: “Withhold a flat 22% (no other percentage allowed).” If no income tax was withheld from your regular wages in that window, Publication 15 says to use the aggregate method, so the flat rate is not available at all.
Yes, but on your return rather than from your employer. Publication 505: “Your employer can't repay any of the tax previously withheld. Instead, claim the full amount withheld when you file your tax return.”
No. 22% is a withholding rate, not a tax rate. A bonus is ordinary income, and the tax you owe is worked out on your whole year on your return. Withholding only decides how much was paid in ahead of that.
Yes, at 6.2%, until your wages for the year reach the Social Security wage base, $184,500 for 2026. After that the 6.2% stops, so the same bonus nets more later in the year. Publication 15 says supplemental wages are subject to Social Security, Medicare and FUTA taxes “regardless of the method you use to withhold income tax”.
Publication 15 gives the rate as 22% “(37% if supplemental wages paid to an employee during the calendar year exceed $1 million)”. It is a running calendar-year total of your supplemental wages from that employer, not a test on one payment. This page does not model the 37% rate.
No. Everything here is an educational estimate of withholding, not tax, payroll or financial advice, and not a Publication 15-T withholding calculation.