Who this applies to
You are an irregular-hours worker if the hours you are paid for in each pay period are wholly or mostly variable under your contract, which often includes zero-hours, casual and bank staff. You are a part-year worker if your contract runs all year but you are only required to work part of it, with unpaid periods of at least a week, as many term-time staff are.
How holiday builds up
For leave years starting on or after 1st April 2024, these workers build up holiday at 12.07% of the hours they actually work in each pay period. Someone who works 86 hours in a month builds up about 10.4 hours of holiday. The figure of 12.07% comes from dividing 5.6 weeks of holiday by the 46.4 weeks left in a year.
Rolled-up holiday pay
For these workers only, employers may choose to pay holiday pay as an extra 12.07% on top of each pay packet instead of paying it when the holiday is taken. It must be shown as a separate line on the payslip. The worker still has the right to take the time off; it is simply paid in advance.
Entitlement and pay are different
The calculator on this site works out how much holiday time you have built up. Holiday pay itself should reflect normal pay, which can include regular overtime, commission and some allowances, not just basic pay.