Bonus Tax Calculator
Separate what is withheld from your bonus from what you actually owe — the flat supplemental rate is a withholding convention, not your tax rate.
Bonus Tax Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Results are a model, not a quotation — an institution's own figures govern.
- Every input is an assumption; change one and the answer changes with it.
- Rounding is applied only at the display layer, so totals may differ by a cent from a statement that rounds each line.
In short: A $12,000 bonus on a $48,000 salary has $2,640 withheld at the flat 22% supplemental rate, but the real federal tax is $1,440 — the bonus falls entirely in your 12% bracket. That is $1,200 over-withheld, 45.5% of the federal withholding, returned only when you file.
Formula
The flat rate is a withholding convention the IRS permits employers to use. Your actual liability depends on where the bonus sits in your brackets.
Worked Example
- Find taxable income without the bonus. $48,000 − $14,600 = $33,400, giving $3,776 of federal tax.
- Add the bonus. $45,400 taxable gives $5,216 — so the bonus itself costs $1,440.
- Note the bracket. The whole bonus fits inside the 12% band, which ends at $47,150 of taxable income.
- Compare with the withholding. The flat rate takes $2,640 — $1,200 more than you owe.
- Net it down. After $918 of FICA and $600 of state tax you receive $7,842, but keep $9,042 once the refund arrives.
Analyst's note. The widespread belief that bonuses are 'taxed higher' is wrong, but it is not baseless — the withholding genuinely is higher for anyone below the 22% bracket. The flat supplemental rate is an administrative shortcut that the IRS permits, and it is deliberately conservative so that employees rarely owe money in April. Here it takes $1,200 too much: an interest-free loan to the government averaging several months. Nothing is lost permanently, but adjusting your W-4 to reflect it is worth doing if bonuses form a large share of your pay.
Strengths & Limits Of This Model
Where this engine is strong
- Runs entirely in your browser — no figure you type is transmitted or stored.
- Shows the full working, so every number can be traced and challenged.
- Free, unmetered and free of affiliate incentives.
Where it stops
- Generalised assumptions cannot capture every individual circumstance.
- Jurisdiction-specific rules and mid-year changes may not be reflected.
- A model output is not a substitute for a professional review of your position.
Practical Use Cases
Working out what a bonus is genuinely worth
The payout figure and the keep figure differ by the refund. Budget on what you keep, not on the deposit or the headline. Feed the real number into the Budget Calculator.
Deciding whether to defer a bonus into your 401(k)
Deferral avoids income tax at your true marginal rate, not the 22% withheld — which is less compelling in a 12% bracket than in a 24% one, and never avoids FICA. Project the compounded balance with the 401k Calculator.
Adjusting your withholding
Persistent large refunds mean you are lending money to the government for free. If bonuses are a regular feature of your pay, a W-4 adjustment converts that refund into monthly cash. Check the effect with the Paycheck Calculator.
Methodology & Editorial Standards
The engine models the percentage method of supplemental withholding: a flat 22% on supplemental wages up to $1m in a calendar year and a mandatory 37% on the excess. Actual federal tax is computed as the incremental liability from adding the bonus to salary under 2024 single-filer brackets, which correctly captures bracket crossing. Employers may instead use the aggregate method, combining the bonus with a regular paycheck and withholding as though that were your normal pay — this typically over-withholds far more dramatically, though the final tax is identical. FICA is applied to the full bonus including any deferred portion, since pre-tax deferral does not exempt wages from payroll tax. Married and head-of-household brackets, credits, itemised deductions and state-specific supplemental rates are not modelled. This is an estimate, not tax advice. The engine implements the standard published formula for this calculation. Inputs are validated for domain and sign before evaluation, and any undefined case returns an em-dash rather than a spurious value.
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Bonus Tax Calculator — 20 Expert FAQs
20 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
Why is my bonus taxed so heavily?
It is not taxed more, it is withheld more. Employers may use a flat 22% supplemental rate regardless of your bracket. On a $48,000 salary the real tax is 12%, so $1,200 of the $2,640 withheld comes back at filing.
Is the 22% a tax rate?
No, it is a withholding convention. Your bonus is ordinary income taxed at your marginal rate like any other earnings. The flat rate exists to simplify payroll and is deliberately conservative.
Will I get the over-withholding back?
Yes, as part of your refund when you file — but not before. In the meantime it is an interest-free loan to the government, which for regular bonus earners is worth correcting through your W-4.
What is the aggregate method?
An alternative in which the employer adds the bonus to a regular paycheck and withholds as though that were your normal pay. It usually over-withholds far more severely, because it annualises a one-off amount. The final tax is unchanged.
What happens to bonuses over $1 million?
Supplemental wages above $1m in a calendar year face a mandatory 37% withholding on the excess. A $1.2m bonus has $220,000 withheld on the first million and $74,000 on the remainder.
Does FICA apply to bonuses?
Yes, in full — 6.2% Social Security up to the wage base and 1.45% Medicare with no cap. Unlike federal income tax, FICA is not over-withheld and is not refunded, and deferring to a 401(k) does not avoid it.
Should I defer my bonus into a 401(k)?
It avoids income tax at your true marginal rate. In a 12% bracket that saves less than most people assume, and it never avoids FICA. In a 24% or 32% bracket the case is considerably stronger.
Can I ask my employer to withhold less?
Not on the supplemental rate itself, which is set by regulation. But you can adjust your W-4 so that regular paychecks withhold less, offsetting the bonus over-withholding across the year.
Does a bonus push me into a higher bracket?
Only the portion above a threshold is taxed at the higher rate, and only if it crosses one. Here the entire bonus stays within the 12% band. Crossing a bracket never reduces your total take-home.
Is a signing bonus taxed differently?
No, it is supplemental income like any other bonus. Note that clawback clauses are common — if you leave early and repay it, recovering the tax already paid can be procedurally awkward.
What about a bonus paid in stock?
Restricted stock units are taxed as ordinary income at vesting on their market value, usually with shares withheld to cover it. Subsequent gains are capital gains — use the Capital Gains Calculator for that portion.
Should I budget on the payout or the keep figure?
The keep figure, but recognise the timing: you receive $7,842 now and $1,200 later. Spending the full $9,042 immediately means borrowing against a refund that may be months away.
Do state taxes work the same way?
Many states have their own flat supplemental rates, others apply normal withholding tables, and nine have no income tax at all. The engine applies a simple flat rate, so verify your state's treatment.
Why do employers use the flat rate?
Because it is simple, defensible and rarely leaves an employee owing money in April — which generates complaints. Over-withholding produces a refund, which does not.
How can I reduce tax on a bonus?
Deferring into a 401(k) or HSA reduces taxable income at your marginal rate. Timing a bonus into a lower-income year helps if you have any control over it. Beyond that, it is ordinary income and there is little room for manoeuvre.
Is this bonus tax calculator free to use?
Yes. It is free, requires no account, and has no usage limits. ApexConverter is funded by contextual advertising, never by selling user data.
Is my data sent to a server?
No. The engine runs as Vanilla JavaScript inside your browser under our Zero-Server Client-Side Execution model. Your figures are computed locally and are never transmitted, logged, or stored.
How accurate is this calculator?
It applies the standard closed-form formula in IEEE-754 double precision, rounding only at the display layer. The engine is reconciled against an independent reference implementation before release.
Does it work on mobile?
Yes. The interface is mobile-first with numeric keypad hints and is tested down to a 320-pixel viewport with no horizontal scrolling.
Can I use it offline?
Largely, yes. Because computation is client-side, the page continues to calculate without a network connection once it has loaded.