Bonus proration explained
Proration decides how much of a bonus you actually earn when you did not work the whole period. The rule is simple; the counting method your employer uses is where the money moves.
Reviewed 20 August 2026 · gross estimates, not payroll or tax advice
What bonus proration actually means
Short answer
Proration reduces a bonus in proportion to how much of the performance period you were actually eligible for. If the plan runs for twelve months and you were eligible for nine of them, you get 9/12 — 75% — of whatever you would otherwise have earned. The performance multipliers are applied to the prorated amount, not the other way round, though the order rarely changes the answer.
Proration exists because a bonus is payment for a period of performance, not a lump sum attached to a job title. Someone who joined in October did not contribute to nine months of results, so most plans do not pay them for those months. The same logic applies in reverse to leavers, to unpaid leave, and to anyone who moved between full-time and part-time hours.
What varies enormously between employers is the counting method. Two companies can both say “we prorate” and produce answers hundreds of dollars apart on the same facts. That is what this guide is about.
When proration applies
The three counting methods
These are the methods you will meet in real plan documents. The differences are small in percentage terms and large in cash terms once salaries get big.
| Method | How it counts | Joined 12 April, 12-month plan |
|---|---|---|
| Calendar days | Eligible days ÷ days in the period. The most precise, and increasingly the default in HR systems. | 264 ÷ 365 = 72.3% |
| Whole months | Complete months of service ÷ 12. Usually a partial month counts only if you started before a cut-off date, often the 15th. | Started after the 15th, so 8 ÷ 12 = 66.7% |
| Payroll periods | Eligible pay periods ÷ total periods. Common where payroll drives the calculation. | 19 ÷ 26 fortnightly = 73.1% |
The formula, and what order things happen in
Multiplication is commutative, so the order of those terms does not change the result — with one important exception. A cap is not a multiplier. If the plan caps payout at 150% of target, it matters enormously whether the cap is applied to the full-year target or the prorated target.
Nearly all plans cap against the prorated target, which is the logically consistent reading: you cannot earn more than 150% of a bonus you were only ever eligible for 75% of. If your plan document is ambiguous, this is a fair question to put to HR in writing.
Worked examples
Example 1 — mid-year joiner. Salary $90,000, target bonus 15%, joined 12 April, company performance 110%, day-count proration.
90,000 × 15% = $13,500 full-year target · × 264/365 = $9,763 prorated target · × 1.10 performance = $10,738. Educational gross estimate only.
Example 2 — part-time all year. Salary quoted full-time equivalent at $80,000, working 0.6 FTE, target 10%, performance 100%. The FTE factor applies to the target: 80,000 × 10% × 0.6 = $4,800. Note that if your salary is already stated as your actual part-time pay rather than the FTE rate, applying 0.6 again would halve your bonus incorrectly — a genuinely common payroll error worth checking.
Example 3 — leaver with a service condition. Salary $120,000, target 20%, resigned on 30 November, plan requires employment on the March payment date. Eligible fraction on a day count would be 92%, giving $22,080 — but the service condition overrides it and the payout is nil. Proration only matters once you clear the eligibility gate.
Run your own numbers in the prorated bonus calculator.
Five mistakes that cost people money
Frequently asked questions
How do you calculate a prorated bonus?
Multiply the full bonus by the fraction of the performance period you were eligible for. With a day count that is eligible days divided by days in the period; with a month count it is complete months divided by twelve. Apply the performance multiplier to the prorated figure, and apply any cap to the prorated target rather than the full-year target.
Do I get a bonus if I joined in the middle of the year?
Usually yes, prorated to your eligible service, provided you meet any minimum service condition. Some plans require three months of service before any bonus accrues, and some require you to have started before a fixed cut-off date to be in the plan at all.
Do I lose my bonus if I resign before it is paid?
Frequently, yes. Many plans require you to be employed and not under notice on the payment date, which can be several months after the period ends. Good-leaver provisions for redundancy and retirement often work differently. This is decided by the plan document, not by proration.
Does unpaid leave reduce a bonus?
Long unpaid absence normally reduces eligible time and therefore the bonus. Statutory parental leave is commonly protected and treated as eligible time even when unpaid, but this varies by country and by employer policy.
Is proration calculated on days or months?
Both are used. Day counting is more precise and is now the more common default in HR systems; whole-month counting is simpler and usually includes a partial month only if you started before a cut-off date such as the 15th. The two methods can differ by several percent of the payout.
How does part-time work affect a bonus?
The target bonus is scaled by your FTE, so a 0.6 FTE employee earns 60% of the full-time target. If you changed hours mid-year, a well-designed plan time-weights the periods rather than applying your year-end FTE to the whole year.
Related tools and guides
Written and reviewed by the BonusPayCalc editorial team. Every formula on this site is shown on the page that uses it, so you can check it against your own plan document. Figures are gross planning estimates and not payroll, tax, legal or HR advice — see methodology.