Sign-on bonuses are taxed as ordinary wage income. The IRS treats them as supplemental wages, which means your employer withholds federal income tax at a flat 22% in most cases, plus Social Security (6.2%), Medicare (1.45%), and any state income tax that applies. Between all of those deductions, roughly 30% to 40% of the bonus typically disappears before it lands in your account. But withholding is only a prepayment. Your actual tax depends on your total income for the year, and depending on your bracket, you may owe more at filing time or get some of it back.
How Federal Withholding Works on a Bonus
Your employer has two ways to calculate federal income tax withholding on a sign-on bonus, and the method they pick changes what you see on the check.
The Flat 22% Method
When the bonus is paid on a separate check from your regular wages, employers almost always use the flat rate method. For 2026, the flat withholding rate on supplemental wages up to $1 million is 22%. On anything above $1 million in supplemental wages for the year, the rate jumps to 37%.1Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide
On a $10,000 sign-on bonus, that’s $2,200 in federal income tax withheld immediately, before FICA or state tax touches it.
The Aggregate Method
If your employer pays the bonus on the same check as your regular wages, they’ll likely use the aggregate method instead. The bonus gets added to your normal pay for the period, and withholding is calculated on the combined amount using your Form W-4 and the standard withholding tables.1Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide The result can look brutal. The tables assume you earn that inflated amount every pay period, so the system briefly treats you as if you make far more than you really do. The excess washes out when you file your return, but the check itself can be jarring.
Social Security and Medicare
On top of income tax withholding, your bonus is hit with FICA: 6.2% for Social Security and 1.45% for Medicare.2Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates Your employer pays a matching share, but that doesn’t reduce yours.
The Social Security piece stops once your total wages for the year hit the wage base, which is $184,500 for 2026.3Social Security Administration. Contribution and Benefit Base Cross that line and Social Security tax stops on the excess. Medicare has no cap and applies to every dollar.
Higher earners pick up another slice. If your wages exceed $200,000 in a calendar year ($250,000 if married filing jointly), an Additional Medicare Tax of 0.9% applies to the amount above the threshold.4Internal Revenue Service. Questions and Answers for the Additional Medicare Tax Those thresholds are fixed by statute and don’t index for inflation. If a big sign-on bonus is what pushes you over the line, the extra 0.9% applies to the portion above it.
State Income Tax on Bonuses
Most states treat bonuses as supplemental wages and apply their own flat withholding rate. These state rates range from roughly 1.5% to over 11%, with most landing between 4% and 6%. A handful of states use their regular progressive wage tables instead, similar to the federal aggregate method. Nine states have no income tax at all, which effectively lowers the total bite on any bonus earned there. Your state’s withholding rules will spell out which rate applies.
The Withholding Rate Is Not Your Actual Tax Rate
This is the piece most people miss. The 22% flat rate is a withholding estimate, not the tax you owe. Your real tax on the bonus depends on your total income for the year and the marginal bracket that income lands in. For many workers, that bracket runs higher than 22%, so the flat withholding falls short and a balance is due in April. For others, 22% overshoots and part of it comes back as a refund.
When you file Form 1040, all your income for the year is combined. The IRS doesn’t distinguish salary dollars from bonus dollars. Total tax is calculated on the whole, the withholding you paid during the year is credited against it, and you either owe the difference or get the overpayment back.5Internal Revenue Service. Instructions for Form 1040
If a large bonus pushes a chunk of your income into the 32% or 35% bracket, you can end up with a real tax bill despite the withholding. The IRS Tax Withholding Estimator at irs.gov lets you run the numbers mid-year so April doesn’t surprise you.
Adjusting Your W-4 If Withholding Falls Short
If the flat 22% won’t cover your actual bracket, you can submit an updated Form W-4 to your employer to raise withholding on the paychecks you have left in the year. Step 4(c) lets you request a specific additional dollar amount withheld per pay period, and Step 4(a) lets you report other income the system should account for.6Internal Revenue Service. Tax Withholding Estimator FAQs This spreads the shortfall across your remaining paychecks instead of leaving you with a lump-sum bill at filing. File a fresh W-4 in January to reset, or you’ll keep over-withholding into the next year.
If You Have to Repay the Bonus
Many sign-on bonuses come with a clawback clause: leave within 12 to 24 months and you owe some or all of it back. The tax fallout depends entirely on when you repay.
Same Year You Received It
Repaying in the same calendar year is clean. Your employer adjusts your wages and issues a W-2 that reflects only the net compensation you actually kept. The federal income tax and FICA originally withheld on the repaid portion get returned to you by the employer, either directly or through payroll. For tax purposes, the bonus effectively never happened.
A Later Year
Repaying in a later year is where it gets messy. You already reported the full bonus as income and paid tax on it. You cannot amend the earlier return, because at the time you received the bonus you had an unrestricted right to it. Relief instead comes through the “claim of right” doctrine under Section 1341 of the Internal Revenue Code.7Office of the Law Revision Counsel. 26 USC 1341 – Computation of Tax Where Taxpayer Restores Substantial Amount Held Under Claim of Right
If the repayment is more than $3,000, you have two options and should calculate both:8Internal Revenue Service. Publication 525 (2025), Taxable and Nontaxable Income
- Deduct the repaid amount on Schedule A for the year of repayment, which reduces taxable income for that year.
- Or calculate what your tax would have been in the original year without the bonus. The difference between what you actually paid and that recalculated amount becomes a credit on the repayment year’s return. This method usually saves more because it offsets tax dollar for dollar rather than just reducing income.
If the repayment is $3,000 or less, only the itemized deduction is available.8Internal Revenue Service. Publication 525 (2025), Taxable and Nontaxable Income For that route to help, you need enough other itemized deductions to clear the standard deduction.
Section 1341 only addresses income tax. It doesn’t recover the Social Security and Medicare taxes you paid on the original bonus. Ask the employer to adjust the overcollection first; if they won’t, you can file Form 843 to claim a refund of the FICA directly from the IRS.9Internal Revenue Service. Instructions for Form 843 – Claim for Refund and Request for Abatement
Ways to Keep More of Your Bonus
You can’t avoid the tax, but you can redirect some of the money to lower current-year income or build long-term savings.
- Raise your 401(k) deferral before the bonus is paid. Most plans include bonuses in eligible compensation, so your elected percentage will come out of the bonus like any other paycheck. If you have room under the 2026 limit of $24,500 (or $32,500 if you’re 50 or older), sheltering more of the bonus defers the income tax. FICA still applies going in.10Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500
- Fund an HSA if you have a high-deductible health plan. 2026 limits are $4,400 for self-only coverage and $8,750 for family, with an extra $1,000 if you’re 55 or older. Payroll HSA contributions dodge both income tax and FICA. Direct contributions still get an income-tax deduction on your return but miss the FICA savings.
- Negotiate a gross-up before you accept. A grossed-up bonus is sized so that after withholding you net the promised amount. The formula is the desired net divided by (1 minus the combined tax rate). Not every employer will agree, but the ones that do are covering the tax for you.
- Time the payment if you can. Taking the bonus in a lower-income year can drop it into a lower marginal bracket; splitting it across two calendar years can smooth the income. This only works if the employer is open to negotiating timing.
None of these eliminate tax on a sign-on bonus. They defer it, shift it into tax-advantaged accounts, or push the cost to the employer. On a five-figure bonus, even modest planning can move real money.