Why bonuses feel over-taxed
A bonus is not taxed at a special higher rate. It is ordinary income, taxed on your return at the same brackets as your salary. What surprises people is the withholding. The IRS treats bonuses, commissions and severance as supplemental wages, and employers withhold on them using one of two methods that often take a bigger bite from the check than your normal paycheck withholding would.
Percentage method: if the bonus is paid separately from regular wages (or identified separately on the same check), the employer withholds a flat 22% for federal income tax on supplemental wages up to $1 million in the calendar year. Anything above $1 million is withheld at 37% with no exceptions. Most large employers use this method because it is simple. On a $5,000 bonus the federal withholding is $1,100, plus $310 for Social Security and $72.50 for Medicare, leaving $3,517.50 before any state tax.
The aggregate method
If the bonus is combined with regular wages on one paycheck without being identified separately, the employer must use the aggregate method: add the bonus to that period's wages, compute withholding on the total as if you earned that much every pay period, then subtract what was already withheld on the regular wages. Because the annualized total lands in a higher bracket, the withholding on the bonus portion is roughly your marginal rate, and sometimes higher. This calculator approximates the aggregate method by applying the marginal bracket you select. For someone in the 12% bracket that is less than 22%; for someone in the 24% bracket or above, it is more.
Neither method changes what you ultimately owe. If 22% was withheld and your marginal rate is 12%, the excess comes back as a refund when you file. If your marginal rate is 32%, you will owe the difference in April unless you adjust your W-4 or make an estimated payment.
FICA, state tax and ways to keep more
Social Security (6.2%) and Medicare (1.45%) apply to bonuses just like regular wages. The Social Security portion stops for the year once your total wages exceed $176,100 (2025), so a year-end bonus for a high earner may skip that 6.2%. State withholding varies: several states have their own flat supplemental rate (California 10.23% on bonuses, New York 11.70%, Pennsylvania 3.07%), some use regular withholding tables, and nine states have no wage income tax. Enter your state's rate to include it.
To reduce the tax actually paid, not just withheld, direct some of the bonus into a pre-tax 401(k) or HSA if your plan allows deferrals from bonus pay; that removes it from taxable income entirely. Ask payroll before the bonus is processed, because the election usually has to be in place ahead of the pay date.