Why does my bonus feel so heavily taxed?

It's withheld more than your normal paycheck, but not actually taxed at a higher rate. The flat 22% federal supplemental rate applies at withholding, which often withholds more than your marginal rate requires. At tax time, the actual tax owed is reconciled and the over-withholding comes back as refund (or under-withholding as tax bill). The total tax on bonus income equals the tax on any other income — it just feels different because the paycheck shows a larger withholding bite.

Can I contribute bonus money to my 401(k)?

Usually yes — most employer plans allow it, but you need to elect it explicitly before the bonus runs through payroll. Contact HR the month before bonus hits. For high earners, this is a significant tax-deferral opportunity: 22-35% immediate federal tax savings on the contributed portion.

What's the difference between flat 22% and aggregate withholding?

Flat 22%: federal tax withheld at a fixed 22% on the bonus amount. Aggregate: bonus added to regular paycheck, full payroll withholding math applied to combined amount as if you earn that rate every pay period (over-withholds). Both methods end up with the same total annual tax at year-end — only the timing of the cash flow differs. Flat 22% is more common at large employers.

Do I pay Social Security tax on my bonus?

Yes, up to the annual wage base ($176,100 in 2026). Once your YTD wages plus bonus exceed the wage base, no more Social Security tax that year. Most W-2 employees pay Social Security on their full bonus because they're below the cap. High earners may have bonuses partially exempt.

What's the additional Medicare tax?

0.9% additional Medicare tax applies to wages above $200,000 (single) / $250,000 (married filing jointly). This is on top of the standard 1.45% Medicare. If your bonus pushes you above the threshold, the portion above is subject to the additional 0.9%.

Should I try to split my bonus across two tax years?

Rarely worth it unless you're right at a bracket boundary. Most bonuses are controlled by the employer's fiscal calendar — you can't usually choose. The scenarios where splitting helps: retiring mid-year (lower bracket next year), large swings in income year-to-year. Talk to a CPA if you have timing flexibility on a six-figure bonus.

Yes. The calculator runs entirely in your browser. Bonus amounts and wage data never touch a server. Export the PDF if you want a record for tax planning or cash-flow projection.

Bonus Tax Calculator

Your $15,000 bonus probably nets less than $9,000

Most employees are surprised by their bonus paycheck. The HR announcement says $15,000. The bank deposit says $8,500-9,500. The missing money isn't a mistake — it's the bonus withholding math the company didn't explain.

Bonuses are supplemental wages. The IRS offers employers two ways to withhold on them. The most common is the "flat 22% supplemental rate" — federal income tax on the bonus is withheld at a flat 22%, regardless of your regular tax bracket. Then Social Security (6.2% up to the annual wage cap), Medicare (1.45%, plus 0.9% above $200k wages), state income tax (0-13.3%), and often state disability insurance are all layered on top.

For a $15,000 bonus, the typical withholding stack is: $3,300 federal + $930 Social Security (if still under the cap) + $217 Medicare + $750 state (at 5%) = $5,197 in withholding. You net $9,803 — about 65% of the headline.

This calculator shows the real math for your specific situation. Plug in the bonus, your withholding method, marginal rate, state rate, and YTD wages. It tells you what hits your bank account.

Flat 22% vs aggregate: which method hurts more

The IRS gives employers two options for withholding on bonuses:

Flat 22% (supplemental method): Federal income tax withheld at flat 22%. Simple, fast. Used by most large employers.
Aggregate method: Bonus is added to your regular paycheck, and withholding is calculated on the combined amount as if you'd earn that much every pay period. This often over-withholds because the payroll system treats the inflated paycheck as your new normal income level.

If your marginal tax rate is below 22% (most people earning less than about $50k), the flat method over-withholds. You'll get the extra back at tax time as a refund.

If your marginal tax rate is above 22% (most people earning above $100k), the flat method under-withholds. You'll owe additional tax at year-end. For a high earner in the 32-37% bracket getting a $50,000 bonus withheld at 22%, that's a $5,000-7,500 under-withholding that creates an unexpected tax bill.

Plan accordingly: if you're a high earner and your bonuses are withheld at 22%, set aside an additional 10-15% of each bonus into a savings account specifically for the April tax bill.

FICA caps and why a big bonus in December is different from one in February

Social Security tax is 6.2% on wages up to the annual wage base ($176,100 in 2026). Above that, no more Social Security withholding for the year.

This creates a quirk: if your bonus pushes your YTD earnings above $176,100 for the first time, only the portion below the cap is taxed for Social Security. The portion above the cap is Social Security-free.

Example: You earn $170,000 YTD by December. You get a $30,000 bonus. The first $6,100 of the bonus (pushing you to $176,100) is taxed at 6.2% = $378. The remaining $23,900 has no Social Security tax. Savings: $1,482 vs. if the same bonus came in February when you'd been at $15,000 YTD.

High earners with multiple bonus events through the year should care about timing. The math favors taking bonuses later in the year after Social Security is capped. For most people earning below $176,100 total, this doesn't apply — Social Security is always 6.2% of the full bonus.

A real case: the year-end bonus surprise

Elena, a senior accountant earning $185,000 base, received a $45,000 performance bonus in December. Her expectation from the announcement: "$45k bonus." Her math: maybe 30% taxes, so $31,500 take-home.

What actually happened on the paycheck:

Gross bonus: $45,000
Federal supplemental (22%): $9,900
Additional Medicare (0.9% on amount above $200k YTD): $227 (portion of the bonus above her $200k threshold)
Medicare (1.45%): $652
Social Security: $0 (already above $176,100 cap)
California state income tax (9.3% effective): $4,185
CA SDI (0.9%): $405

Total withheld: $15,369. Net bonus: $29,631. About 66% of headline.

But the actual tax owed was higher than withheld. Her marginal federal rate was 32%, not 22%. At tax time in April, she owed an additional $4,500 on the bonus — the under-withholding from the flat 22% rate. Net true take-home: $25,131, about 56% of headline.

Lesson: for high earners, headline bonus numbers overstate take-home by 10-15% above what normal withholding math would suggest because of the flat-22 under-withholding gap. Always set aside extra when a bonus is expected.

The 401(k) and HSA opportunity most miss

One often-missed strategy: if your employer allows you to direct bonus income into 401(k) contributions, you can shield 22-35% of the bonus from federal tax entirely.

Example: On a $20,000 bonus, contributing 50% to your 401(k) = $10,000 pretax contribution. At a 24% federal bracket, that saves $2,400 in federal tax immediately. Social Security, Medicare, and state tax usually still apply (varies by state), but the federal tax saving is real and immediate.

Caveats: check with HR about bonus 401(k) contribution rules — some employers default bonuses to zero 401(k) contribution unless you opt in. Also watch the annual 401(k) limit ($23,500 in 2026 for under-50); if you're already maxing contributions through regular paychecks, bonus contributions will bounce back.

Similarly, if you have a high-deductible health plan, you can direct bonus dollars into HSA ($4,300 individual / $8,550 family limits in 2026) — fully pre-tax for federal, FICA, and (in most states) state.

For someone in the 32% bracket with a $30,000 bonus: $15,000 to 401(k) + $4,300 to HSA = $6,176 of tax savings compared to taking the full bonus as cash. The cash number drops but your after-tax wealth increases.

Signing bonuses: different rules, same math

Signing bonuses use the same withholding rules as performance bonuses, but two additional considerations:

Clawback clauses. Most signing bonuses come with a repayment obligation if you leave the company within 1-2 years. Typical clause: 100% repayment if you leave in year 1, 50% if you leave in year 2. If clawed back, you repay the gross amount — but you've already paid tax on it. Recovering that tax in a later year is complex; often you lose 10-20% of the gross amount to tax friction even in repayment.
Net vs gross offers. Some companies will gross up the signing bonus to net a specific amount ("$10,000 net to you after taxes"). This is rare but valuable for executive-level hires. Ask the recruiter if grossing up is possible, especially if the offered bonus is relatively small ($5-15k).

Use signing bonuses for one-time uses: moving expenses, paying off high-interest debt, or an emergency fund top-up. Don't let them disappear into lifestyle creep.

Retention bonuses and the golden handcuffs

Retention bonuses are paid to keep you at the company through a specific date, often during acquisitions, restructurings, or for key personnel. Common terms: $25-75k paid in 1-2 installments if you stay through a specific milestone date.

Tax math is the same as any other bonus — flat 22% supplemental federal typically. But two strategic considerations:

The bonus is cheap insurance for the employer, not a promotion. If you receive a retention bonus, it usually means the employer wants specifically you to stay, often because the specific role is hard to rehire. This is negotiating leverage — if they need you enough to pay a bonus, they likely have budget for a permanent base raise as well. Ask for both.
Cliff structure matters. A retention bonus paid in one lump at the cliff date creates strong retention pressure. One paid across the year (monthly or quarterly installments) creates weaker retention pressure but also gives you flexibility. Companies typically prefer cliff structures; negotiate for installments if possible.

After receiving a retention bonus: update your resume, keep interviewing quietly for alternatives, and assume the company is preparing for changes that might hurt non-retained employees. Your job security is higher than others' but your long-term prospects at this company may still be uncertain.

State income tax: the wildly different bonus impact

State tax on bonuses varies dramatically:

Zero tax states: Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington, Wyoming. Bonus is federal and FICA only.
Low tax states: Most Midwest, Southeast, and Mountain West (3-5% on bonuses).
Moderate tax states: Most Northeast, Wisconsin, Georgia, North Carolina, Michigan (5-7%).
High tax states: California (up to 13.3%), New York (up to 10.9%), Oregon (up to 9.9%), Minnesota (9.85%), Hawaii (11%), New Jersey (10.75%).

For a $50,000 bonus: zero tax state saves $5,000-6,500 vs a high tax state on the same income. For remote workers who can choose their state, this is a real line item. A California remote worker who could move to Texas saves roughly $25-35k/year in state income tax on a $250k total comp.

For state withholding, most states apply their standard rate to supplemental wages. A few use a flat supplemental rate (California: 10.23% on bonuses; New York: about 11.7%). Check your state's rules if you need precise withholding numbers.