For leave years starting on or after 1 April 2024, UK employers can calculate holiday entitlement for irregular hours and part-year workers as 12.07% of hours worked in each pay period. Holiday pay is then either paid as rolled-up holiday pay at 12.07% of total pay (separately itemised on the payslip) or paid at the worker's 52-week average earnings when leave is actually taken.
The starting point: 5.6 weeks for everyone
Every UK worker is entitled to a statutory minimum of 5.6 weeks of paid annual leave per leave year · that's the rule under regulation 13 and 13A of the Working Time Regulations 1998. The 5.6 weeks limit is set in weeks, not days, so it works equally well for full-time, part-time, and irregular hours staff.
For a worker on fixed regular hours, that 5.6 weeks translates neatly into days · someone working 5 days a week is entitled to 28 days, someone on 3 days a week is entitled to 16.8 days, and so on. We've covered that in detail in our annual leave entitlement guide and the part-time pro-rata guide.
For irregular hours and part-year workers, the picture is different. Their working hours don't neatly translate into days or weeks at the start of the leave year, so the law lets the entitlement build up as they work, rather than being granted up front.
Who counts as an irregular hours or part-year worker
The Working Time Regulations 1998, as amended by the Employment Rights (Amendment, Revocation and Transitional Provision) Regulations 2023, give two distinct definitions:
Irregular hours worker
Someone whose paid hours each pay period during the term of their contract are wholly or mostly variable under the contract. ACAS gives the example: Sam is paid weekly and works a different number of hours each week. The contract says hours will vary each week. Sam is an irregular hours worker.
Typical examples: zero-hours contract staff, casual workers, bank workers, some agency workers.
Part-year worker
Someone required to work only part of the year under their contract, with periods within the year of at least one week when they are not required to work and are not paid.
Typical examples: term-time-only school staff, seasonal hospitality workers, exam invigilators.
The two calculation methods
For irregular hours and part-year workers there are really two questions to answer. First, how much leave does the worker accrue? Second, what does each week of holiday get paid at? The 2024 reforms give employers options on both.
| Step | Method | How it works |
|---|---|---|
| Entitlement | 12.07% accrual | 1 hour of leave accrues for every 8.28 hours worked |
| Pay | Rolled-up holiday pay | 12.07% of total pay added to each pay period, itemised separately on payslip |
| Reference period method | Pay holiday at the worker's average over the previous 52 paid weeks when leave is actually taken |
Employers can mix and match · use 12.07% accrual for entitlement and the 52-week reference period for pay. Or use 12.07% accrual for entitlement and rolled-up holiday pay for the pay element. What employers cannot do is use rolled-up holiday pay for fixed-hours workers, or use the old "pay holiday at average earnings only" approach without doing the 12.07% accrual maths.
Method 1: 12.07% accrual
The 12.07% number isn't arbitrary. It's the proportion that 5.6 weeks of holiday bears to the 46.4 working weeks of the year:
Each pay period, the worker accrues holiday equal to 12.07% of the hours they worked. Part-hours are rounded down to the nearest hour if less than 30 minutes, and rounded up to the nearest hour if 30 minutes or more (per ACAS guidance and the Working Time Regulations).
If the worker gets more than 5.6 weeks of holiday
Where the contract gives more than the statutory 5.6 weeks of holiday, the percentage is recalculated. The formula is (total holiday weeks / remaining working weeks of the year) x 100:
| Holiday weeks | Working weeks | Calculation | Accrual rate |
|---|---|---|---|
| 5.6 (statutory minimum) | 46.4 | 5.6 / 46.4 | 12.07% |
| 6.0 | 46.0 | 6.0 / 46.0 | 13.04% |
| 6.6 (5.6 + 1 wk extra) | 45.4 | 6.6 / 45.4 | 14.54% |
| 7.0 | 45.0 | 7.0 / 45.0 | 15.56% |
Worked example
Calculator: 12.07% accrual
Use this calculator to work out leave accrual for an irregular hours worker over a single pay period. It uses the statutory minimum 12.07% rate; if your contract gives more than 5.6 weeks, override the percentage in the box below.
Method 2: rolled-up holiday pay
Rolled-up holiday pay means paying the holiday pay element at the same time as basic pay each pay period, rather than separately when the worker actually takes leave. It became lawful again for irregular hours and part-year workers from leave years starting on or after 1 April 2024 · the law had previously been unclear after the European Court of Justice's 2006 Robinson-Steele decision.
The mechanics are simple. For each pay period:
All earnings for hours worked in that period · basic pay, overtime, shift premiums, regular allowances. Anything that would otherwise count as "normal pay" for holiday pay purposes.
For example, total earnings £1,000 in June -> rolled-up holiday pay = £120.70 in June. The two amounts are paid together but shown as separate items on the payslip.
The Working Time Regulations expressly require rolled-up holiday pay to be shown as a separate payment on the payslip · "basic pay £1,000 / rolled-up holiday pay £120.70". Without separate itemisation, the holiday pay does not satisfy the worker's entitlement.
Worked example: rolled-up pay
Method 3: pay holiday at the time using the 52-week reference period
If you choose not to use rolled-up holiday pay, you must pay the worker for their holiday at the time they take it. The amount is based on the worker's average pay over the previous 52 paid weeks:
The 52 weeks ending on the day before the holiday starts. If the worker has been employed for less than 52 weeks, use the actual number of weeks they have worked.
Weeks where the worker did no work and was not paid are excluded from the average. You can look back up to a maximum of 104 weeks to fill 52 paid weeks. Weeks of statutory leave (maternity, sickness etc.) are excluded · skip them.
Total pay across the 52 paid weeks divided by 52. That's the worker's "week's pay" for holiday purposes.
When the worker takes a week of holiday, they're paid the average. For half-weeks or single days, calculate proportionally based on their typical working pattern over the 52-week reference period.
This method is more administratively complex than rolled-up pay but it remains the default UK approach for fixed-hours workers · and it stays available for irregular hours workers if you'd rather not use the rolled-up route. For deeper context on what "normal pay" includes, see our guide on how holiday pay is calculated in the UK.
Common employer mistakes
Five issues come up repeatedly in tribunal cases and ACAS guidance:
A worker on a 2-week rotating shift pattern · even with different hours each week · is on fixed hours, not irregular hours. The 12.07% method and rolled-up pay are not available. Apply the standard 5.6-week entitlement and 52-week reference period for pay instead.
If holiday pay is wrapped invisibly into the hourly rate, it does not satisfy the entitlement. Tribunals will treat the holiday as untaken and unpaid. The Working Time Regulations require a separate payslip line.
The 2024 reforms only apply to leave years starting on or after 1 April 2024. Earlier leave years remain governed by the previous rules. For employers with a January-to-December leave year, the changeover happened on 1 January 2025.
Holiday accrual continues during maternity, paternity, adoption, shared parental, and parental bereavement leave. For irregular hours workers, the relevant period for working out the average pay during these leaves runs from the day before the leave started, going back 52 weeks, excluding weeks not worked due to the family leave or sickness.
Statutory holiday cannot be paid in lieu except on termination of employment. The Working Time Regulations are health and safety legislation; the leave itself must be taken. Rolling up the pay does not remove that duty.
Sources
| Source | What it covers |
|---|---|
| Working Time Regulations 1998 | The primary UK law on holiday entitlement (regulations 13 and 13A) and pay (regulation 16) |
| Employment Rights (Amendment, Revocation and Transitional Provision) Regulations 2023 | The 2023 amendments that introduced the 12.07% method and re-permitted rolled-up holiday pay from 1 April 2024 |
| GOV.UK · Holiday pay and entitlement reforms from 1 January 2024 | The official government employer guidance with worked examples for both methods |
| GOV.UK · Calculate leave entitlement | The simple GOV.UK tool and rules for irregular hours and part-year accrual |
| ACAS · Irregular hours and part-year workers | Plain English guidance on definitions, examples and calculations |
| ACAS · Rolled-up holiday pay | Specific guidance on the 12.07% rolled-up calculation, payslip itemisation and worked examples |
Frequently asked questions
How do you calculate holiday pay for irregular hours workers in the UK?
For leave years starting on or after 1 April 2024, UK employers can calculate holiday entitlement for irregular hours and part-year workers as 12.07% of hours worked in each pay period. Holiday pay is then either delivered as rolled-up holiday pay at 12.07% of total pay each pay period (shown as a separate line on the payslip), or paid at the worker's average earnings over the previous 52 worked weeks when leave is actually taken.
Why is the holiday accrual rate 12.07% for irregular hours workers?
12.07% reflects the proportion that the statutory minimum 5.6 weeks of holiday bears to the 46.4 working weeks of the year (52 · 5.6 = 46.4; 5.6 / 46.4 = 0.1207). It is the UK statutory minimum for workers who only get the 5.6-week entitlement. Where a contract gives more than 5.6 weeks of holiday, employers must use the formula (total holiday weeks / remaining working weeks) x 100 to find the right percentage · for example, 6 weeks of holiday gives 13.04%.
What is rolled-up holiday pay and is it legal in the UK?
Rolled-up holiday pay means paying an enhanced rate for hours worked instead of paying separately when leave is taken. It became lawful again for irregular hours and part-year workers from leave years starting on or after 1 April 2024. Rolled-up pay is calculated at 12.07% of total pay each pay period and must be itemised separately on the payslip. It cannot be used for fixed-hours workers and the employer must still ensure the worker actually takes their statutory leave.
Who counts as an irregular hours worker?
Under the Working Time Regulations 1998, as amended in 2024, an irregular hours worker is someone whose paid hours each pay period are wholly or mostly variable under the terms of their contract. ACAS confirms this typically includes zero-hours, casual and bank workers. Workers on a fixed shift pattern · even if hours differ from week to week · are not irregular hours workers. A part-year worker is one required to work only part of the year with at least one week of unpaid breaks during the contract.
How do you work out holiday pay if rolled-up pay isn't used?
When the employer chooses not to use rolled-up holiday pay, holiday pay is calculated using the 52-week reference period method. You take the worker's average weekly earnings over the last 52 paid weeks (excluding any unpaid weeks where the worker did no work), and pay that average for each week of holiday taken. If the worker has been employed for less than 52 weeks, the period is shortened to the actual weeks worked. If the period needs to extend past 52 weeks to reach 52 paid weeks, you can go back up to 104 weeks.
Do the new holiday pay rules apply retrospectively?
No. The 12.07% accrual method and rolled-up holiday pay regime apply only to leave years starting on or after 1 April 2024. Leave years that started before that date continue to be governed by the previous rules until they renew. A leave year running 1 January to 31 December would only switch to the new rules from 1 January 2025 onwards.