Short answer: Pro rata salary = full-time salary × your hours ÷ full-time hours. A £30,000 full-time salary at 22.5 of 37.5 hours a week is £18,000 a year.
General information, not tax or financial advice. Check GOV.UK or speak to a qualified adviser about your own situation.
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Holiday entitlement is pro-rated in the same way: 5.6 weeks × your days per week.
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What is the formula, in plain text?
Pro rata salary = full-time salary × (your hours per week ÷ full-time hours per week). The same works with days: full-time salary × (your days ÷ full-time days). Statutory holiday = 5.6 weeks × your working days per week.
What rates and thresholds apply?
Item
Value
Statutory holiday entitlement
5.6 weeks a year (capped at 28 days)
What are some worked examples?
Full-time salary
Full-time week
Your week
Pro rata salary
£30,000
37.5 hours
22.5 hours
£18,000
£25,000
5 days
3 days
£15,000
£42,000
40 hours
30 hours
£31,500
£36,000
37.5 hours
15 hours
£14,400
Holiday example: 3 days a week × 5.6 = 16.8 days. The 5.6-week figure is long-standing statutory entitlement but was not part of tonight's GOV.UK rate check; confirm on GOV.UK.