Bonus and supplemental-wage calculator

Checked on 2026-10-28. Source: IRS Publication 15 (2026), "What's New" and section 7 (fetched and read 2026-10-28: 'the withholding rate on supplemental wages remains 22% (37% if supplemental wages paid to an employee during the calendar year exceed $1 million)').

When your employer pays a bonus, commission, or other supplemental wage separately from your regular paycheck, the IRS allows it to withhold federal income tax at a flat rate rather than running it through your regular W-4 brackets. This calculator applies that flat-rate method so you can see what a bonus check is likely to withhold before it lands.

Why the rate can jump to 37 percent

The flat rate on supplemental wages is 22 percent, but the IRS requires the higher rate of 37 percent once your cumulative supplemental wages from one employer pass $1,000,000 in the calendar year. This almost never affects a typical annual bonus, but it matters for a large commission year, a big severance payment, or a signing bonus on top of other supplemental pay already received. Enter what you have already been paid in supplemental wages this year to see whether this payment crosses that line.

What this is, and is not

This is withholding, the amount your employer sends to the IRS on your behalf, not your final tax bill on the bonus. A bonus is taxed at your regular income tax rate when you file your return; the flat withholding rate is only a shortcut for how much is held back now. If the flat rate withholds more than your actual tax rate on that income, you get the difference back as part of your refund; if it withholds less, you may owe more at filing. This tool also does not include Social Security or Medicare, which still apply to a bonus at the same rates as regular wages; see our paycheck calculator for those.