The pro rata formula
pro rata salary = full-time salary × (your hours ÷ full-time hours) × (weeks worked ÷ 52)
The calculator also lets you set how many months of the tax year you are employed. Joining in October, for example, means you earn half a year’s pay in this tax year but still have the whole £12,570 personal allowance — which is why people starting mid-year often pay less tax early on, or get a refund.
Worked example: 3 days a week on a £32,000 job
£32,000 FTE, 22.5 of 37.5 hours, England, 2026/27
22.5 ÷ 37.5 = 60%, so the salary is £19,200. Most of it is within the personal allowance and basic rate band, leaving £17,344 a year after tax and NI.
- Take-home per month
- £1,445
- Hourly rate
- £16.41
- Earned this tax year
- £19,20012 months
Part-time pay
- Full-time salary
- £32,000.00
- Hours ratio
- 60.0%
- Pro-rata annual salary
- £19,200.00
- Income tax
- −£1,326.00
- National Insurance
- −£530.40
- Take-home per year
- £17,343.60
A term-time role on the same pattern for 39 weeks a year earns £14,400 before tax. In practice many school contracts add paid holiday on top of the weeks worked; check how your employer calculates the “weeks paid” figure.
Part-time rights
- Holiday is pro rata: 5.6 weeks of your normal working pattern, so 16.8 days for a three-day week.
- Bank holidays don’t have to be given on top, but part-timers must not lose out compared with full-timers.
- Pension auto-enrolment applies once you earn over £10,000 a year with one employer.
- Sick pay: Statutory Sick Pay is £123.25 a week from April 2026.
Things that change your take-home
Two part-time jobs each pay you a salary, but only one gets your personal allowance; the other uses code BR, taxing everything at 20%. If the second job is small, you can ask HMRC to split your allowance between the two.