Flat supplemental withholding

Bonus Tax Calculator

What actually lands from a bonus. Employers withhold a flat IRS supplemental rate on a separately paid bonus, not the rate your salary implies, which is why it looks over-taxed.

Your numbers

What actually lands from a bonus

Employers withhold a flat IRS rate on a bonus paid separately, not the rate your salary implies. That is why it looks over-taxed.

WITHHOLDING, NOT TAX

A flat rate comes out now. What you owe is settled on your return.Tax year 2026 · IRS Publication 15 (Circular E), section 7 · State source shown in the result

Bonus amount$Before anything is taken out

Regular wages paid so far this year$Decides how much Social Security is left to pay

Bonuses already paid this year$Only matters near the $1 million mark

State

Filing status

What lands in your account

$7,035.0029.6% of the bonus withheld, on a $10,000 bonus

Federal withholding$2,200.00Flat 22% supplemental rate

Social Security$620.00Continues from wages so far

Medicare$145.00No wage cap

State$0.00Texas

Total withheld$2,965.0029.6%

Texas is estimated from its annual schedule as the extra tax this bonus adds, not from a state supplemental rate.

How we got this

Federal withholding at 22%$10,000 of the bonus, the flat supplemental rate$2,200.00
Social Security6.2% up to the $184,500 wage base$620.00
Medicare1.45% with no cap$145.00
StateTexas annual schedule, marginal effect of the bonus$0.00
What lands29.7% of the bonus withheld in total$7,035.00

What we assumed

This is withholding, not tax. A flat percentage comes out at payout; what you actually owe on the bonus is settled with the rest of your income on your return, and the difference comes back as a refund or is owed.
Federal withholding uses the IRS flat supplemental rate of 22%, and 37% on supplemental wages above $1,000,000 in a calendar year. Source: Publication 15 (2026), (Circular E), Employer’s Tax Guide, section 7.
That assumes your employer pays the bonus separately and uses the flat-rate method. An employer may instead add the bonus to a regular paycheck and withhold from the IRS wage tables, which usually withholds a different amount.
Social Security and Medicare are not flat-rated. They continue from the wages you have already been paid this year, which is why the Social Security cap and the additional Medicare threshold depend on the figures you enter.
Retirement deferrals, benefit premiums, garnishments, and local taxes are not modeled.
This is an estimate of a paycheck, not tax advice.

Technical details

Method bonus-tax-v1.0.0Data us-tax-2026-v1

Guide

Why a bonus can look over-taxed on the stub

CostAnswer editorialIndependent calculator publisher

When a bonus is paid separately from regular wages, employers often withhold a flat IRS supplemental rate instead of the rate your salary implies. This page shows that withholding, not your eventual refund or bill.

Supplemental wage withholding

The IRS lets employers withhold a flat percentage on separately paid bonuses, commissions, and similar supplemental wages (up to a high-dollar threshold that uses a different method). That flat rate is often higher than your average tax rate, which is why the deposit looks small.

When you file, the bonus is just more ordinary income in your bracket. Withholding is not the tax. A large bonus can still increase your total tax; it does not stay taxed at the flat supplemental rate forever.

What this page does not do

It does not model aggregate supplemental wages over the IRS threshold method, state supplemental rates in every jurisdiction, or a bonus added to a regular paycheck (which may use the aggregate method instead). Signing bonuses, severance, and commissions follow the same idea only when they are paid as supplemental wages.

Questions about this calculator

Why is my bonus taxed so much?

The stub is usually flat supplemental withholding, not your marginal rate applied forever. Compare the Method version with the rate printed on the stub. Your tax return will recompute the whole year.

Is a signing bonus withheld the same way?

Often yes if it is paid separately as supplemental wages. If it is rolled into a regular paycheck, the employer may use a different method. This page models the flat separate-payment case.

Does state tax use the same flat rate?

Not always. Some states piggyback on federal supplemental rules; others have their own. The page uses the state treatment in the snapshot, and will not invent a rate it does not have.

Terms used here

Supplemental wages: Bonuses, commissions, overtime paid separately, and similar amounts the IRS distinguishes from regular wages for withholding.
Flat withholding: A single percentage taken from a separately paid bonus, not a full annualized bracket calculation.
Aggregate method: Adding the bonus to regular wages and withholding as if the total were a single paycheck.

Practical tips

If the bonus hits the same check as regular pay, this flat-rate picture may not match the stub.
Plan cash around withholding, then wait for the return to settle the real tax.
A traditional 401(k) deferral on the bonus, if your plan allows it, changes taxable wages; this page only models what you type.

Limits and caveats

Withholding is not your final tax. This is not tax advice.
High-dollar supplemental wages can switch IRS methods. That switch is not fully modeled.

Results are for information. They are not legal, tax, medical, or financial advice. How the math is maintained · Report a wrong figure.

Engine notes

Rounding, versioning, and omissions that sit beside the guide rather than repeating it.

Why a bonus looks over-taxed. When a bonus is paid separately from regular wages, the IRS lets an employer withhold a flat 22% instead of using your Form W-4 and the wage tables. That rate has nothing to do with your salary, so someone in a lower bracket sees too much taken and someone in a higher bracket sees too little. Either way it is trued up when you file.
Above a million dollars. Once supplemental wages paid to one person pass $1,000,000 in a calendar year, the excess must be withheld at 37%, regardless of what your W-4 says. Only the part over the line takes that rate, which is why earlier bonuses in the same year matter.
FICA and state are not flat. Social Security stops at the yearly wage base and the additional Medicare tax starts at a threshold, so both depend on what you have already been paid this year. State withholding rules for supplemental wages differ by state and are not published as one table, so the state figure here is the extra tax the bonus adds under that state’s annual schedule.

Calculation receipt

What each number here is

This answer is built from published figures. Each one is named below, with the release it came from.

VERIFIEDIRS and state revenue departments: Sets the figures this answer is made of. Without it the page says so rather than estimating.

If a source above is unavailable or out of date: Supplemental withholding is a published IRS rate. Without the 2026 tables there is no withholding figure to give, and last year’s rate would be a wrong answer rather than an old one.

Sources

Where this data comes from

Internal Revenue ServicePublication 15 (2026), (Circular E), Employer’s Tax Guide, section 7. Flat 22% supplemental rate, and 37% above the yearly threshold. Snapshot us-tax-2026-v1.Verified 2026-09-04 ↗Internal Revenue ServiceRevenue Procedure 2025-32, used for the bracket data behind the rest of the tax tools.IRS · Tax year 2026 ↗Social Security AdministrationOASDI contribution and benefit base. Social Security wage base and rates for 2026.Tax year 2026 ↗