A radiology signing bonus is taxed as supplemental wages, not as regular salary, and that distinction changes how much of the check actually reaches your account. This guide walks through the exact withholding math that applies in 2026, using a $30,000 bonus as the working example so you can substitute your own number.
- IRS taxes radiology signing bonus payments as supplemental wages: 22% federal withholding on amounts up to $1 million in 2026.
- A $30,000 signing bonus nets roughly $19,600 to $21,100 after federal, FICA, and state withholding, depending on where you practice.
- Bonuses that push total supplemental wages over $1 million in a calendar year get withheld at 37% federally, not 22%.
- Withholding is not your final tax bill — your actual bracket at filing determines the after-tax value of a radiology signing bonus.
- Compare full offers, not just the bonus line, before you sign a contract.
Why this matters
Recruiters quote signing bonuses as round numbers — $25,000, $40,000, $75,000 — and most radiologists mentally bank the full figure. The IRS doesn't see it that way. A bonus paid as a lump sum triggers a different withholding rule than your salary, and that rule alone can shrink the check by close to a third before state tax even applies.
The gap between the headline number and the deposit in your account is where a lot of new attendings get surprised on their first paycheck. Knowing the math ahead of time lets you negotiate with a clearer head and compare offers from radiology jobs with signing bonuses in 2026 on equal footing.
How do you calculate the after-tax value of a radiology signing bonus?
The IRS classifies a signing bonus as a supplemental wage. Under the flat-rate method most employers use, federal income tax is withheld at 22% on supplemental wages up to $1 million paid to you in a calendar year — this is a fixed federal rule, not a guess by your employer's payroll department. On top of that flat rate, standard payroll taxes still apply:
| Withholding component | Rate | Applies to |
|---|---|---|
| Federal supplemental wage withholding | 22% | First $1 million in supplemental wages per calendar year |
| Federal supplemental wage withholding (excess) | 37% | Amount over $1 million in supplemental wages per calendar year |
| Social Security | 6.2% | Wages up to the annual Social Security wage base |
| Medicare | 1.45% | All wages |
| Additional Medicare Tax | 0.9% | Wages over $200,000 (single) or $250,000 (married filing jointly) |
| State income tax | 0% to 13.3% | Varies by state of residence and total income |
Run a $30,000 signing bonus through that stack and here's what lands in your account:
| Scenario | Federal (22%) | Social Security (6.2%) | Medicare (1.45%) | State tax | Net bonus |
|---|---|---|---|---|---|
| No state income tax (e.g., Texas, Florida) | $6,600 | $1,860 | $435 | $0 | $21,105 |
| Moderate state tax (5%) | $6,600 | $1,860 | $435 | $1,500 | $19,605 |
| High state tax (9%) | $6,600 | $1,860 | $435 | $2,700 | $18,405 |
Verdict: expect $19,600 to $21,100 in your account on a $30,000 signing bonus, depending almost entirely on your state of residence. Scale the percentages up or down for a different bonus amount — the math doesn't change, only the inputs do.
Signing bonuses over $1 million: withheld at 37%, not 22%
If your total supplemental wages in a calendar year (signing bonus, relocation bonus, and any other bonus payments combined) cross $1 million, the IRS mandates a flat 37% federal withholding rate on the amount over that threshold, instead of 22%. This almost never applies to a single radiology signing bonus, but it matters if a large sign-on payment lands in the same year as a retention bonus or a productivity bonus from a prior employer.
“Withholding is not your tax bill — it is a deposit against it.”
Why the after-tax value varies
The net figure on your bonus check moves for reasons that have nothing to do with the bonus amount itself:
- State of residence. Nine states charge no state income tax; California's top marginal rate runs as high as 13.3%. This single variable often swings the after-tax value by thousands of dollars.
- Total annual income and marginal bracket. The 22% federal withholding is a flat administrative rate, not your real tax rate. If your combined income puts you in the 32% or 35% federal bracket, you'll owe more at filing time than what was withheld.
- Filing status and deductions. Married filing jointly, itemized deductions, and retirement contributions all shift what you actually owe versus what got withheld.
- Timing of payment. A bonus paid in December versus January can change which tax year it counts against, which matters if you're near a bracket threshold.
- Repayment or clawback clauses. Many radiology contracts require repaying a prorated portion of the bonus if you leave before a set term — reducing the effective after-tax value if you don't stay the full period. Reading the fine print before signing matters here; the radiology employment contract is where these clauses live.
- Retirement plan elections. Pre-tax 401(k) or 403(b) contributions taken from the bonus reduce the taxable amount up front, changing the net.
Do you get back over-withheld signing bonus tax at tax time?
Yes — if the flat 22% federal withholding exceeds what you actually owe based on your marginal bracket, the difference comes back as part of your refund when you file. This is common for radiologists whose effective tax rate lands below 22% after deductions, and it's why the withholding amount and the true after-tax cost of the bonus are two different numbers.
Is a signing bonus subject to FICA the same way as salary?
Yes — Social Security (6.2%) and Medicare (1.45%) apply to a signing bonus exactly as they apply to regular wages, with the same annual Social Security wage base cap. There's no exemption for bonus income on the FICA side, only on the federal income tax withholding method.
Should you ask for a grossed-up signing bonus?
A grossed-up bonus means the employer pays extra to cover the tax hit, so you net the full advertised figure — worth raising in negotiation, especially if the bonus is the deciding factor in comparing two offers. Not every group will agree to it, but it costs nothing to ask, and it's a cleaner ask than trying to renegotiate base salary after signing.
Running the after-tax math on a bonus is one piece of comparing offers — base salary, RVU thresholds, call schedule, and benefits usually move the needle more over a full year. RadBoard aggregates listings from 20 sources so you can filter by compensation structure before you're deep in a single negotiation.
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FAQ
Is a radiology signing bonus taxed differently than salary?
Yes — the IRS treats a signing bonus as supplemental wages and withholds federal tax at a flat 22% (up to $1 million per year) instead of using your regular payroll withholding table. Social Security and Medicare still apply the same as they do to salary.
How much tax is withheld from a radiology signing bonus?
Expect roughly 30% combined federal and FICA withholding before state tax: 22% federal supplemental withholding, 6.2% Social Security, and 1.45% Medicare. State income tax adds 0% to 13.3% on top, depending on where you live.
Do you get back over-withheld signing bonus tax at tax time?
Yes, if your actual marginal tax bracket is below 22%, the excess withholding comes back as part of your refund when you file. If your bracket is above 22%, you'll owe the difference instead.
What happens if my signing bonus pushes me into a higher tax bracket?
The bonus itself doesn't get taxed at a higher rate just because it's added on top of salary — only the income that actually falls into the higher bracket is taxed at that rate. The 22% withholding may simply undershoot what you owe at filing.
Is a signing bonus subject to Social Security and Medicare tax?
Yes, a signing bonus is subject to the standard 6.2% Social Security tax (up to the annual wage base) and 1.45% Medicare tax, the same as regular wages, with no bonus exemption.
Can I negotiate a grossed-up signing bonus?
Yes, some radiology groups will agree to gross up a signing bonus so you net the full advertised amount after tax. It's a reasonable ask during offer negotiation, though not every employer will accommodate it.
Is a large signing bonus taxed at 37% instead of 22%?
Only the portion of your total supplemental wages over $1 million in a calendar year gets withheld at 37% federally. A typical radiology signing bonus stays well under that threshold and is withheld at 22%.
Does a repayment clause affect the after-tax value of a signing bonus?
Yes — if your contract requires repaying a prorated share of the bonus for leaving early, the effective after-tax value drops if you don't complete the required term, since you'd be repaying pre-tax dollars with after-tax income.
One last thing
The number most radiologists overlook isn't the tax rate — it's the repayment clause. A bonus with a two-year clawback provision can turn a $30,000 signing bonus into a net loss if you leave the position after 14 months, since you typically repay the gross amount, not the after-tax amount you actually received. Read that clause before you read the compensation number.
