Bonus Tax Calculator (2026)

Bonus withholding is not bonus tax

Employers pay bonuses as wages. They are subject to federal income tax, Social Security, and Medicare like salary. What frustrates people is withholding on the bonus check itself—often a flat 22% federal rate (for supplemental wages under $1 million) or an aggregate method that combines the bonus with a regular paycheck for table lookup. That withholding is a prepayment, not the final tax rate on the bonus.

This calculator shows supplemental withholding estimates and places the bonus in your annual tax picture using 2026 brackets and standard deductions from Rev. Proc. 2025-32. Compare stub shock today with April reality tomorrow.

2026 payroll context for bonuses

• Flat supplemental federal rate: 22% on supplemental wages under $1 million (37% on excess over $1 million)
• Social Security: 6.2% until YTD wages reach $184,500 wage base
• Medicare: 1.45% on all bonus dollars; Additional Medicare Tax may apply above $200,000 wages
• Standard deduction still applies at filing: $16,100 single, $32,200 joint—not on the bonus stub itself

Flat rate vs aggregate method

Flat rate method: Employer withholds 22% federal on the bonus alone (plus FICA). Simple, often feels harsh on small bonuses for low-bracket workers but may under-withhold for high earners already in the 32%+ bands.

Aggregate method: Employer adds bonus to regular wages for one period and runs Publication 15-T tables as if that inflated paycheck were normal—can produce weird spikes when the period looks like you earn $30,000 every two weeks.

Employers pick allowed methods; employees rarely choose. Knowing which method hit your stub explains stub vs annual gaps.

How to use the calculator

Step 1 — Enter bonus amount and YTD wages

YTD wages matter for Social Security cap and Additional Medicare Tax. A December bonus after maxing the base skips 6.2% Social Security even though income tax withholding continues.

Step 2 — Select supplemental method

Compare flat 22% vs aggregate if you know employer practice. If unsure, run both.

Step 3 — Layer annual income

Add salary and other income so marginal rate reflects total 2026 tax, not the bonus in isolation.

Step 4 — Tune W-4 if needed

Use the W-4 withholding calculator after a surprise bonus to spread corrections across remaining paychecks.

Worked example ($10,000 bonus, flat 22%, single, 2026)

$10,000 bonus, flat supplemental withholding:

• Federal income tax withheld ≈ $2,200 (22%)
• Social Security $620 if base not maxed; Medicare $145
• Net check ≈ $7,035 before state and other deductions

If annual taxable income after $16,100 standard deduction keeps you mostly in 12% and 22% bands, true marginal tax on the bonus might be lower than 22%—refund potential. If you are already in the 32% band, 22% withholding may underpay—balance due risk.

Bonus plus 401(k) deferrals

Some employers allow bonus deferral into 401(k) up to the $24,500 annual limit—reducing taxable wages now. Roth 401(k) deferrals on bonuses still owe income tax withholding on the deferral portion. The 401(k) calculator shows headroom.

RSUs and equity bonuses

RSU vesting is wage income too—withholding varies by employer sell-to-cover policies. Use the RSU tax calculator for equity-specific flows; this bonus tool fits cash performance bonuses and similar payments.

State tax on bonuses

States often withhold on bonuses separately from federal methods. This page is federal-focused. Add state in the state income tax calculator or job offer comparison when location matters.

Common mistakes

• Believing “22% bonus tax” is a separate IRS surtax—it is withholding
• Ignoring Social Security cap when projecting December net bonus
• Forgetting bonus in quarterly estimates for freelancers who also take W-2 bonuses
• Not updating W-4 after a large bonus skews remaining-year withholding
• Comparing bonus net to salary net without annualizing salary first

Related tools

Model regular take-home in the paycheck calculator. Build annual liability in the federal income tax calculator. See payroll tax detail in the FICA calculator. Close the year with the tax refund estimator.

Negotiating gross vs net bonuses

Employers quote gross bonus amounts; cash in hand is net. When comparing offers, run gross through this tool with your filing status and YTD wages so “$15,000 retention bonus” is not mistaken for $15,000 spendable.

Multiple bonuses in one year

Performance bonuses, signing bonuses, and retention payouts stack into the same annual wages bucket. A second $20,000 bonus late in the year may face 22% federal withholding again while your marginal rate on the return is already 32%—underwithholding risk. Conversely, a first bonus early in the year may over-withhold for workers who stay in lower brackets all year. Model cumulative salary plus all bonuses in the federal income tax calculator before spending net proceeds.

401(k) match true-ups and bonus timing

Some employers calculate 401(k) match on bonuses separately from base salary, affecting deferral headroom toward the $24,500 limit. If your bonus hits after you maxed deferrals on salary, you may miss match dollars unless the plan true-ups at year-end—plan document detail, not tax law, but it changes net wealth alongside tax.

Commission and equity treated like bonuses

Sales commissions paid outside regular salary cycles often use supplemental withholding too. Equity bonuses (cash-settled) follow wage rules; RSU vesting is covered elsewhere but shares the same “withholding ≠ final tax” lesson. When commission spikes one month, aggregate withholding can look like you earn that amount every pay period—bracket tables over-withhold compared with flat 22% in some cases, under-withhold in others.

After any large supplemental check, rerun the tax refund estimator with updated YTD withholding so April does not surprise you.

Net bonus after FICA in December

If you already maxed the $184,500 Social Security wage base, a year-end bonus skips the 6.2% slice—net pay jumps compared with an identical gross bonus in March. Medicare still applies. Model December bonuses with YTD wages entered; the FICA calculator shows the payroll-tax side in isolation.

Sources and methodology

Supplemental withholding rates follow IRC §3402(a) and Publication 15, Section 7. Annual tax stacking uses Rev. Proc. 2025-32 brackets and 2026 standard deductions. FICA uses SSA’s $184,500 wage base. Results are educational withholding and liability estimates—not employer payroll instructions.