The Straight Answer: How to Calculate Bonus Tax in 2025–2026
If you want to know how to calculate bonus tax, start with this: the IRS treats bonuses as ‘supplemental wages’ and gives employers two ways to withhold federal income tax—a flat 22% rate (or 37% above $1 million) known as the percentage method, or the aggregate method that folds the bonus into your regular paycheck and uses your normal bracket. On top of federal withholding, you owe FICA: 6.2% Social Security up to the wage base and 1.45% Medicare, plus a 0.9% Medicare surtax if you earn over $200K single or $250K married. State tax varies.
For a quick reality check, a $5,000 bonus under the flat method costs about $1,100 in federal withholding, $382.50 in FICA, and perhaps $250 in a 5% state, leaving roughly $3,267 net. A $10,000 bonus runs about $2,200 federal, $765 FICA, $500 state, net $6,535. Those are withholding estimates, not final tax. The actual tax on your bonus is determined when you file, based on total income and bracket.
I’ll show you a manual worksheet to compute this without any online tool, but if you prefer automation, our Bonus Tax Calculator applies these same rules instantly. Either way, the key is separating the federal supplemental layer from payroll taxes and state.
Why the ‘25% or 40%’ Bonus Tax Question Is Outdated
A question I still hear from coworkers: are bonuses taxed at 25 or 40 percent? That myth comes from pre-2018 law when supplemental wages were withheld at 25% and 39.6% (not 40%) above $1 million. The Tax Cuts and Jobs Act dropped the top rate to 37% and the supplemental rate to 22%, where they remain for 2025 and 2026.
When I first processed a year-end bonus for a small business client in late 2017, I mistakenly used the old 25% figure on an $8,000 payout, over-withholding by $240. The employee got a larger refund, but the cash-flow timing hurt his December plans. The thing nobody tells you about legacy payroll software is that some default tables lag federal changes by a full cycle.
The Current IRS Rates, Straight From the Source
The legal basis is in IRS Publication 15 (Circular E), which confirms the 22% supplemental rate for amounts up to $1 million and 37% above that. These are withholding rates, not your effective tax rate. If your marginal bracket is 12%, you’ll likely get a refund on the excess; if you’re in the 32% bracket, you’ll owe more at filing.
Most people don’t realize that the flat 22% is often higher than their actual bracket for moderate earners, which is why bonuses feel ‘taxed more’—it’s a withholding timing difference, not a higher tax law.
The Two IRS Methods for Bonus Tax Withholding
To calculate bonus tax correctly, you must know which method your employer uses. The percentage method is the simple flat 22% (or 37%) on the bonus alone. The aggregate method adds the bonus to your regular pay period wages and withholds as if that combined amount were your normal pay, using the wage bracket or percentage method tables.
Percentage Method (Flat Withholding)
This is what most large companies use for discretionary bonuses. It’s clean: $5,000 × 0.22 = $1,100 federal. No need to know your other income. It fails, however, to account for your true bracket, which can mean over- or under-withholding.
Aggregate Method (Treated as Regular Wages)
Here’s where the manual math gets interesting. Suppose your normal biweekly pay is $3,000 and you receive a $5,000 bonus in the same check. The payroll system treats $8,000 as periodic wages. It annualizes or uses tables to compute withholding on $8,000, then subtracts what would have been withheld on $3,000. The difference is applied to the bonus.
For a low-income worker, this can result in less than 22% taken out—sometimes near 0% if total annual income stays in the 10% bracket. The trade-off: aggregate can be more accurate but is volatile. If your regular pay fluctuates, the bonus withholding swings. I’ve seen a $10K bonus withheld at only 8% for a part-time employee whose annual income was low, creating a surprise tax bill later.
Your Manual Bonus Tax Worksheet: Step-by-Step
Below is the framework I use when advising clients. It requires only a pen, your pay stub, and the current tax tables. This directly answers the practical question: how do you calculate your bonus? You calculate the tax by isolating the supplemental amount and walking through five steps.
Step 1: Identify the Gross Bonus Amount
The gross bonus is the number on your contract or approval letter before any deductions. If your employer uses a formula from a pool, our Bonus Pool Calculator can help model the split, but for tax you just need the final dollar figure. Write it at top of worksheet.
Step 2: Choose Federal Method and Compute Income Tax
If percentage method: multiply by 0.22 (or 0.37 over $1M). If aggregate, take your regular period wages + bonus, find withholding from IRS tables for that combined amount, subtract withholding on regular wages alone. Record the difference. For annualized aggregate, multiply combined periodic pay by number of periods, compute tax on that annual figure, divide by periods, then subtract regular tax.
Step 3: Layer in FICA — Social Security and Medicare
FICA applies to bonuses just like wages. For 2025, Social Security tax is 6.2% on wages up to $168,600 (base indexed; check SSA’s current wage base). Medicare is 1.45% with no cap, plus 0.9% additional Medicare tax if your YTD wages exceed $200K (single) or $250K (married filing jointly). Most $5K–$10K bonuses won’t hit the surtax unless YTD is already high.
Step 4: Add State Income Tax
State treatment varies wildly. Some states like Pennsylvania flat 3.07%, others like California use progressive brackets that mimic federal aggregate. For a manual estimate, use a flat 5% if your state has moderate rate, or look up your bracket. Multiply bonus by state rate. If your state has no income tax, enter zero but still account for local taxes.
Step 5: Compute Net Take-Home
Subtract federal income tax + FICA + state from gross bonus. That’s your net. Compare to your actual stub; if numbers differ by more than a few dollars, check for local taxes, 401(k) loan repayments, or garnishments. This worksheet is reusable for any bonus size.
Worked Example: $5,000 Bonus for Single and Married Filers
Let’s answer the common search: how much tax will I pay on a $5000 bonus? We’ll use the percentage method first. Assume a single filer, no other complications, and a state with 5% flat rate.
Single Filer, $5K Bonus, Flat 22%
Federal withholding: $5,000 × 0.22 = $1,100. FICA: SS $310 (5,000×0.062) + Medicare $72.50 (5,000×0.0145) = $382.50. State: $250. Total tax $1,732.50. Net $3,267.50. That’s the straightforward answer.
Married Filer, $5K Bonus, Flat 22%
The federal flat rate is identical regardless of filing status—22%—so federal stays $1,100. FICA identical $382.50. State may differ if married rates lower; using same 5% flat, state $250. Net same $3,267.50. But if the state uses brackets, married may pay slightly less.
What If Aggregate Method Applies to the $5K Bonus?
Imagine the same single filer earns $4,000 per month ($48K annual) and gets $5K bonus in March. Regular monthly federal withholding on $4,000 might be ~$380 (using 2025 tables). Combined $9,000 monthly equivalent annualizes high, but tables compute per-period. The withholding on $9,000 might be $1,150, minus $380 = $770 attributed to bonus. That’s 15.4% effective federal, not 22%.
So the answer to ‘how much tax will I pay on a $5000 bonus’ depends on method. At year-end, true tax on $53K income for single is about $6,300 total; the bonus portion in 12% bracket is $600 federal, meaning the percentage method over-withheld by $500. The refund arrives months later.
Worked Example: $10,000 Bonus and Hidden Variables
Now the other frequent query: how much tax is taken out of a $10,000 bonus? Again, start with flat method.
Single, $10K Bonus, Flat 22%
Federal: $2,200. FICA: $620 SS + $145 Medicare = $765. State 5%: $500. Total $3,465. Net $6,535. Straightforward and matches most stubs.
Married, $10K Bonus, Aggregate at Different Income Brackets
If a married couple has household income $80K and bonus hits in a paycheck with $6,000 regular wages, aggregate may withhold based on $16,000 period. Using rough extrapolation, federal on $16K period could be ~$1,800, on $6K ~$450, difference $1,350 on bonus = 13.5%. FICA still $765, state maybe $400. Total ~$2,515, net $7,485. The aggregate method saved $950 versus flat.
That’s why knowing your method matters. The flat 22% is a default, not a mandate; employers may switch methods year to year. Always read the stub’s notation.
The $1 Million Trigger and Additional Medicare
Neither $5K nor $10K hits the 37% tier, but if your bonus exceeds $1 million, federal flat jumps to 37%. Also, if YTD wages plus bonus push you over $200K (single), the 0.9% Medicare surtax applies to the excess. On a $10K bonus for someone already at $195K YTD, $5K of it incurs 0.9% extra = $45. Most people miss this line on their stub.
Quick-Reference Table: Common Bonus Amounts and Estimated Withholding
Use this table for flat-method, single, 5% state, ignoring surtax. Adjust for your bracket and method. It answers ‘how do you calculate your bonus’ net for planning purposes.
| Gross Bonus | Federal 22% | FICA 7.65% | State 5% | Total Tax | Net Take-Home |
|---|---|---|---|---|---|
| $1,000 | $220 | $76.50 | $50 | $346.50 | $653.50 |
| $5,000 | $1,100 | $382.50 | $250 | $1,732.50 | $3,267.50 |
| $10,000 | $2,200 | $765 | $500 | $3,465 | $6,535 |
| $20,000 | $4,400 | $1,530 | $1,000 | $6,930 | $13,070 |
| $50,000 | $11,000 | $3,825 | $2,500 | $17,325 | $32,675 |
Remember, this is withholding, not final tax. If your marginal rate is lower, you’ll recover the difference; if higher, you’ll owe. The table is a starting point, not a substitute for the worksheet.
State Tax Integration and Reciprocity Gotchas
Federal rules are uniform, but states fracture the picture. Nine states have no income tax (e.g., Texas, Florida), so bonus tax stops at FICA. Others like New York and California tax bonuses as regular income, often via aggregate only. If you work remotely across state lines, reciprocity agreements may mean only your resident state taxes the bonus.
I once advised a client in Pennsylvania working temporarily in New Jersey; the employer withheld NJ tax on the bonus incorrectly because they used percentage method without checking reciprocity. We filed a refund claim. The lesson: always verify state withholding code on your stub against your resident state.
Local Taxes and Hidden Layers
Some cities (Philadelphia, New York City) add local wage taxes of 3–4%. These apply to bonuses too. A $10K bonus in NYC could lose an extra $400 to city tax beyond state. The competitor articles rarely mention this, but it’s real money that changes net take-home.
Common Mistakes and What Can Go Wrong
The manual worksheet is powerful but fragile. A frequent error: forgetting the Social Security wage base. If you’ve already earned $168,600 YTD, the 6.2% drops to 0 on the bonus, lowering FICA to 1.45%. Missing that overstates tax by $310 on $5K.
Another: assuming 22% is your tax. It is not. When you file, the bonus is added to ordinary income. If you’re in 24% bracket, the flat 22% under-withholds by 2% plus potential surtax. You’ll owe at April. I’ve seen $10K bonuses generate $200–$800 unexpected bills for professionals who ignored this.
Most people don’t realize that if your employer uses aggregate in a high regular-pay period, the bonus can be withheld at 32% or more, making the net smaller than the table above. Always request a separate bonus stub if possible to see the isolated calculation.
When to Use a Calculator vs. Doing It by Hand
The worksheet builds intuition; a tool saves time. Our Bonus Tax Calculator lets you toggle percentage vs aggregate, input YTD wages, and select state. Use it for year-end planning. But if you’re negotiating a bonus structure, the manual steps help you see levers—like timing the bonus in a low-income period to use aggregate advantage.
For business owners splitting profits, the Bonus Pool Calculator models allocations before tax. The limitation: no calculator knows your full itemized deductions or credit eligibility, so final liability still requires Form 1040. Treat tools as estimators, not authorities.
Final Takeaways: Effective Tax Rate vs. Flat Withholding
Calculating bonus tax is not mysterious once you separate the layers. The IRS supplemental rate of 22% is a withholding convenience, not a tax sentence. Your true tax on a $5,000 or $10,000 bonus equals your marginal rate on that slice of income, plus FICA, plus state. For many, that’s lower than 22%, yielding a refund; for high earners, it’s higher.
Use the worksheet, check the method on your pay stub, and adjust withholding via Form W-4 if you consistently see large swings. That’s the practitioner’s path to keeping more of your bonus in your pocket throughout the year.