A “pro-rata” salary is a full-time salary scaled down to the hours you actually work, or to the part of the year you actually work. Job adverts often quote a full-time-equivalent (FTE) figure followed by “pro-rata” — meaning the real pay depends on your hours. This guide explains how pro-rata pay is worked out, and the part people find most confusing: how PAYE taxes it across the year.
To turn an FTE salary into your actual pay, use the Pro-Rata Calculator. To see the tax and National Insurance on it, use the Take-Home Pay Calculator.
1. How pro-rata pay is calculated
There are two common scenarios:
Part-time (fewer hours per week)
You scale the FTE salary by the ratio of your hours to full-time hours.
Pro-rata salary = FTE salary × (your hours ÷ full-time hours)
Example: a role advertised at £35,000 FTE for a 37.5-hour week, worked at 22.5 hours, pays £35,000 × (22.5 ÷ 37.5) = £21,000 a year.
Part-year (starting or leaving mid-year)
You scale the annual salary by the fraction of the year you work — usually by days or by whole months.
Pay = annual salary × (days employed ÷ 365)
Example: a £35,000 salary starting on 6 October 2026 (so you work the second half of the 2026-27 tax year) pays roughly £35,000 × (182 ÷ 365) ≈ £17,452 for that tax year.
2. The key tax point: PAYE is cumulative
This is where part-year starters often pay too little tax early on, then more later — or get a refund. PAYE normally works on a cumulative basis: each payday, your employer looks at your total pay and total tax-free allowance for the year so far, not just this month.
Your Personal Allowance of £12,570 (2026-27, frozen) is spread evenly across the year — about £1,048 a month. If you start work partway through the tax year on a cumulative code, you get the benefit of all the allowance that built up while you were not working.
That means a part-year starter often pays little or no tax in their first month or two, because months of unused allowance are released at once.
3. Worked example: starting mid-year
Sam starts a £35,000 job on 6 October 2026 — exactly halfway through the 2026-27 tax year. Monthly gross pay is £35,000 ÷ 12 = £2,916.67.
- By month 7 of the tax year (the first month Sam is paid), the cumulative tax-free allowance is 7 × £1,048 = £7,336.
- Sam’s cumulative pay is only £2,916.67, which is below the accumulated allowance — so in that first month Sam pays £0 income tax.
- Tax then kicks in over the following months as cumulative pay catches up with the running allowance.
- Over the full part-year, Sam earns about £17,452 — comfortably above the £12,570 allowance — so tax is due on roughly £4,882, but it is collected gradually, not all at the start.
National Insurance, by contrast, is not cumulative — it is worked out each pay period independently, on earnings above the primary threshold for that period. So Sam pays NI from the first payslip even though income tax is £0 that month.
4. Watch-outs
- Emergency or W1/M1 code: if you start without a P45, you may be put on a non-cumulative code and overpay; this corrects once HMRC issues a cumulative code. See Emergency Tax Codes Explained.
- Leaving mid-year: if you stop work partway through the year, you may have overpaid because the allowance kept being applied; a refund follows after the year ends (or sooner via a P800).
- Two part-time jobs: your Personal Allowance is usually set against one job; the second is often taxed at BR (20%). The combined position is still correct over the year.
Work out your real pay
Pro-rata maths plus cumulative PAYE makes part-year and part-time pay hard to eyeball. Use the Pro-Rata Calculator to scale the salary, then the Take-Home Pay Calculator for the tax and National Insurance on it.