Holiday Entitlement Calculations: UK Employer Guide

Every worker in the UK has a statutory right to 5.6 weeks of paid holiday per year. For a full-time worker working five days a week, that is 28 days including bank holidays. Part-time workers receive a pro-rata entitlement: a worker doing three days a week receives 16.8 days. The calculation looks straightforward — but irregular hours and variable pay create complexity.

The 2023 Supreme Court ruling in Harper Trust v Brazel and subsequent legislative changes — applied through ERA 2025 — reformed holiday pay calculations for irregular-hours workers. The rolled-up holiday pay method is now permitted for genuine irregular-hours workers, at 12.07% of earnings in each pay period. For regular workers, holiday pay must reflect normal pay — including regular overtime and commission — calculated over a 52-week reference period.

Mellow calculates holiday entitlement and pay automatically based on the employee's contract type and working pattern. Rolled-up holiday pay is supported for zero-hours and casual workers. For regular employees, the 52-week reference period calculation is applied to ensure overtime and commission are included in holiday pay. Getting holiday pay wrong is one of the most common sources of tribunal claims — and claims can go back two years.