Why your bonus paycheck lost 22% (and more)
Bonuses are "supplemental wages," and employers may withhold at a flat federal 22% regardless of your actual bracket — no standard deduction proration, no W-4 nuance, just 22% off the top, plus FICA on every dollar and your state’s supplement rate (often a flat 4-7%). On a $10,000 bonus as a single filer: $2,200 federal withholding, $765 FICA, maybe $450 state — the check lands near $6,585 and feels like theft. It is not. Withholding is a prepayment, not a price. The calculator separates what was withheld from what is actually owed, because the gap between them is your April refund.
What the bonus really costs at filing
At filing, your $10,000 bonus is just income stacked on your $85,000 salary. A single filer at $85,000 sits in the 22% bracket already, so the bonus dollars land at 22% marginal — the flat withholding happens to be exactly right, and the refund on the bonus is roughly zero (state may still refund a little). But a filer earning $48,000 (top bracket 12%) also had 22% withheld — $1,000 too much, refunded in April. And a $250,000 earner in the 35% bracket had $1,300 too little withheld, owed at filing. Same flat 22%, three different outcomes — which is the entire argument for running the number before spending the check.
The aggregate method — when your employer adds bonus to a regular check
The alternative to flat-22% is the aggregate method: the bonus is added to a normal paycheck and withholding runs through the W-4 tables on the combined amount. One-time spikes can push a combined check into absurd withholding territory — a $10,000 bonus added to a $2,900 paycheck with single-standard W-4 settings can temporarily look like a 32%+ rate. Neither method changes your true tax; they only change the timing of the prepayment. If your employer uses aggregate and the check looks brutal, the annual return trues it up — this calculator’s "true cost" line is the same under either method.
The 2026 OBBBA twist: qualified overtime is different
If part of the "bonus" is overtime pay, 2026 has a new wrinkle: up to $12,500 of qualified overtime ($25,000 joint) is an above-the-line deduction, reducing federal taxable income while your employer still withholds normally on it. A worker earning $52,000 with $8,000 of overtime gets the overtime taxed at an effective rate well below their 22% bracket because the deduction pulls taxable income back down the bracket ladder. Tips have a parallel, larger deduction ($25,000 cap). If your variable pay is overtime or tips, run it through the income tax calculator with the deduction fields filled — the bonus number overstates the cost in exactly that case.
Practical moves before the bonus lands
Three legitimate levers. Time a 401(k) contribution to the bonus paycheck — pre-tax deferral shrinks both federal withholding and (in most plans) FICA, and many plans let you set a one-paycheck-only election at 50-100% of that check. Check whether your plan has a true-up on the employer match if you are already near the $24,500 elective deferral ceiling for 2026. And if your true marginal rate is far from 22%, adjust W-4 line 4(c) in advance: high earners add extra withholding to avoid an April surprise. None of this changes the tax; all of it changes which month the cash arrives.
Estimates for planning only — not tax, legal or accounting advice. Your actual return depends on facts this tool does not ask about. Figures are based on IRS Revenue Procedure 2025-32 (tax year 2026), verified October 2026.