12.07% holiday accrual for irregular-hours and part-year workers

Where this applies: Great Britain (England, Wales and Scotland). The regulations below are marked as extending to England, Wales and Scotland on legislation.gov.uk. Northern Ireland has separate holiday rules and is not covered. Not legal advice.

For leave years beginning on or after 1 April 2024, irregular-hours and part-year workers in Great Britain build up holiday as they work, at 12.07% of the hours worked in each pay period. The rule is in regulation 15B of the Working Time Regulations 1998.

Who it applies to

Regulation 15F(1) defines both groups, in relation to a leave year:

• Irregular-hours worker: “the number of paid hours that they will work in each pay period during the term of their contract in that year is, under the terms of their contract, wholly or mostly variable”.
• Part-year worker: “required to work only part of that year and there are periods within that year (during the term of the contract) of at least a week which they are not required to work and for which they are not paid”.

The test is the contract, not last month’s hours. Regular-hours workers, full- or part-time, keep the 5.6-week entitlement (reg 13 and 13A).

The rule, step by step

1. Start date. Reg 15B(1): it applies “in respect of any leave years beginning on or after 1st April 2024”. For earlier leave years, GOV.UK says leave “does not need to be accrued based on hours they’ve already worked”.
2. When and how much. Reg 15B(3)(b): leave accrues “on the last day of each pay period at the rate of 12.07% of the number of hours that they have worked during that pay period”.
3. Rounding. Reg 15B(5): a fraction of an hour “is to be treated as zero if it is less than 30 minutes and one hour if it is 30 minutes or more than 30 minutes”.
4. Cap. Reg 15B(4): a worker “cannot, in any leave year, accrue more than 28 days of annual leave under this regulation”.
5. Leave year. Reg 15B(7): the date in a relevant agreement or, if none, the start of employment and “each subsequent anniversary of that date”.
6. No buying out. Reg 15B(6): the leave “may not be replaced by a payment in lieu except where the worker’s employment is terminated”.

GOV.UK’s worked example: a worker paid weekly who worked 30 hours has earned 4 hours’ leave (30 × 12.07 ÷ 100 = 3.621, rounded up).

Our own illustration

This is our illustration, not a figure from the legislation or GOV.UK. A worker paid weekly works 68 hours in one week and 23 the next:

Things the 12.07% rule doesn’t settle on its own

• Sick and statutory leave. Leave also accrues during sick or statutory leave, on a separate 52-week average under reg 15C.
• Carry-over. Under reg 15D, leave may only be taken in the year it accrues, except where a relevant agreement allows part to be carried forward, or where statutory or sick leave, or the employer’s failure to give a reasonable opportunity, prevented it.
• Holiday pay. How much each hour of leave is paid is a separate rule: see the 52-week average and rolled-up holiday pay.

What Leaveproof does

• Accrues 12.07% of hours worked on each pay period’s last day for irregular-hours and part-year workers in leave years from 1 April 2024, and rounds each period’s accrual as reg 15B(5) says (our reading; another reading rounds the running total).
• Gives regular-hours workers 5.6 weeks of their weekly hours, capped at 28 days and pro-rated for joiners and leavers.
• Applies the 28-day cap when you give a day length; without one it can’t convert hours to days and does not apply it.
• Infers the worker type from the hours pattern when the export doesn’t say, and always flags that inference so you confirm it from the contract.
• Flags irregular-hours workers in leave years before April 2024, shown as 5.6 weeks of average hours, an approximation of the earlier rules.

Leaveproof reads a payroll export saved as CSV, one row per worker per pay period (or per pay item), plus the employer’s leave sheet if there is one. It is designed for exports from Xero Payroll UK and BrightPay, but their report columns are chosen by the user and have not been checked against every layout, so Leaveproof shows the columns it detected and asks you to confirm which is which before it works anything out. It remembers that choice for each employer. Any payroll software that can export pay periods, pay, hours and holiday columns to CSV can be used the same way.

What it doesn’t do

• It doesn’t calculate reg 15C accrual during sick or statutory leave; it flags it so you can add it as an adjustment.
• It doesn’t decide which carry-over exception applies; it flags unexplained carry-over.

More guides

• Holiday records from 6 April 2026: what GB employers must keep
• Rolled-up holiday pay: the 12.07% uplift and who it can be used for
• Holiday pay 52-week average: weeks with no pay and the 104-week look-back
• Holiday pay when someone leaves: payment in lieu of untaken leave
• Carrying over holiday to the next leave year

Not legal advice. This guide summarises the statutory minimum rules in the Working Time Regulations 1998 as they apply in Great Britain (England, Wales and Scotland), checked against legislation.gov.uk and GOV.UK on 27 October 2026. Contracts, collective agreements and individual cases can change the answer; take advice on a specific case. Leaveproof is independent and not affiliated with or endorsed by Xero or BrightPay. Xero is a trademark of Xero Limited; BrightPay is a trademark of Bright Software Group.