Holiday entitlement and holiday pay for irregular-hours workers: an employer guide

Irregular-hours and part-year workers are the population where UK holiday goes wrong most often, and the reason is structural rather than careless: since leave years beginning on or after 1 April 2024, these workers are not on the familiar entitlement at all. The Working Time Regulations 1998 give them an accrued entitlement under reg 15B instead, paid under a reg 16 mechanism that imports the Employment Rights Act 1996 with its own modifications. This guide sets out who is in scope, how entitlement accrues, what must be included when you pay it, which reference period applies, and when rolled-up holiday pay is lawful.

TL;DR

• Irregular-hours and part-year workers accrue 12.07% of the hours worked in each pay period, on the last day of that pay period, capped at 28 days a leave year (reg 15B(3)(b), 15B(4)).
• “5.6 weeks” is not a statutory phrase. It is four weeks under reg 13(1) plus 1.6 weeks under reg 13A(2)(e), with the aggregate capped at 28 days by reg 13A(3) — and regs 13(A1) and 13A(A1) switch both off for reg 15B workers.
• A week’s pay must include task-linked commission, status and seniority payments, and regularly-paid overtime (reg 16(3ZA)).
• The reference period is 52 weeks in which pay was payable (reg 16(3)(e)(ii)). The 104-week figure is a conditional bound under reg 16(3)(f)(i), not a default window.
• Rolled-up holiday pay — a 12.07% uplift on remuneration for work done — is lawful for reg 15B leave and no other leave (reg 16A(1)–(2)), and the itemised pay statement must show it (reg 16A(7)).
• Accrual during sick or statutory leave runs on reg 15C’s three-step calculation, not on 12.07% of hours worked.

Two different questions need two different tools. gov.uk’s holiday entitlement calculator returns a quantity — days, shifts or hours — and never a monetary figure. Taito.ai’s holiday pay calculator returns money: what a given period of leave is worth under reg 16.

Which of your workers count as irregular-hours or part-year workers?

Only the ones who meet the definitions in reg 15B, for leave years beginning on or after 1 April 2024. That is a narrower test than “anyone whose hours move about”, and getting it wrong is costly in both directions.

For a worker inside the definitions, reg 15B does not sit alongside the ordinary entitlement — it replaces it. Reg 13(1) is expressly restricted by reg 13(A1)(b) to “a worker to whom regulation 15B does not apply in respect of any leave years beginning on or after 1st April 2024”, and reg 13A carries the same switch. So there is no 5.6 weeks to pro-rate for these workers. There is one accrued entitlement, built up pay period by pay period.

For a worker outside them, 12.07% accrual has no statutory footing. A part-timer on a fixed two-day week has ordinary entitlement under regs 13 and 13A; applying an accrual percentage to them is a decision you would have to defend on its own terms, not a rule the WTR supplies.

Two related points sit at guidance level rather than in the regulations. gov.uk’s holiday entitlement guidance states the ordinary entitlement as 5.6 weeks and describes bank holidays as capable of counting toward it — that is guidance, not a WTR provision, and no regulation states it. Treat the contract as the governing document on bank holidays and do not cite the WTR for the point.

How much holiday does an irregular-hours worker accrue?

At 12.07% of the hours worked in each pay period, credited on the last day of that pay period. Reg 15B(3) puts it this way: an irregular-hours or part-year worker accrues leave “(a) during any period of sick leave or statutory leave, in accordance with regulation 15C, and (b) otherwise, 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.” Reg 15B(2) then defines the balance at any moment as accrued leave, plus leave carried forward, less leave taken.

Two mechanical rules follow. Reg 15B(4): “a worker cannot, in any leave year, accrue more than 28 days of annual leave under this regulation.” And reg 15B(5) rounds a fractional hour up to a full hour once it reaches 30 minutes, dropping anything less.

Entitlement and pay for irregular-hours workers at a glance

One caveat the holiday pay calculator states and this guide repeats: the reg 15B(4) cap is expressed in days while accrual is measured in hours, and the regulation supplies no conversion between them. That conversion needs a normal-day-length assumption, so the tool flags the cap rather than silently applying it. Do the same in your own records: hold the accrual in hours and check the cap deliberately.

What counts as normal remuneration when you pay holiday?

Reg 16(1) entitles a worker to be paid “at the rate of a week’s pay in respect of each week of leave” for leave under regs 13, 13A and 15B, and reg 16(2) imports ERA 1996 ss.221 to 224 subject to the modifications that follow. For reg 15B leave, reg 16(1A) converts that into an hourly rate by the formula “A÷B”, where A is the week’s pay and B is the average number of hours worked in each week used to calculate A.

The substance of “a week’s pay” is in reg 16(3ZA): “In the case of entitlement under regulations 13 and 15B the following types of payments are to be included when determining the amount of a week’s pay … (a) payments, including commission payments, which are intrinsically linked to the performance of tasks which a worker is obliged to carry out under the terms of their contract; (b) payments for professional or personal status relating to length of service, seniority or professional qualifications; (c) other payments, such as overtime payments, which have been regularly paid to a worker in the 52 weeks preceding the calculation date.”

Now the part that is routinely over-stated. Reg 16(3ZA) names entitlement under regs 13 and 15B. Reg 13A’s 1.6 weeks is not in that list. Three things follow, and all three matter:

1. Reg 13A leave is still paid a week’s pay under reg 16(1), imported from ERA 1996 ss.221 to 224 as modified by reg 16(3). It is not exempted from reg 16.
2. Because reg 13A pay is what remains once the reg 16(3ZA) components are set aside, it is derived rather than independently measured. Calling reg 13A leave “basic pay” overstates the difference.
3. Nothing in the WTR orders reg 13 leave against reg 13A leave when a worker takes some of each. Taking reg 13 leave first is a convention, not a statutory ordering rule, and the calculator discloses it as an assumption rather than presenting it as law.

For a reg 15B worker the split does not arise at all, because regs 13(A1) and 13A(A1) have switched those entitlements off. There is one entitlement, paid at one rate.

Which reference period do you use — 52 weeks or 104?

52 weeks, with 104 as a conditional outer bound. Reg 16(3)(e) replaces the twelve-week references in ERA 1996 ss.221(3), 222(3) and (4), 223(2) and 224(2) and (3) with “(i) in the case of a worker who on the calculation date has been employed by their employer for less than 52 complete weeks, the number of complete weeks for which the worker has been employed, or (ii) in any other case, 52”.

Reg 16(3)(f) then applies only “in any case where section 223(2) or 224(3) applies” — the case where a week is skipped because no remuneration at all was payable for it. In that case, and only in that case, “account were not to be taken of remuneration in weeks preceding the period of 104 weeks ending” with the relevant week. So 104 weeks bounds how far back you may reach while hunting for paid weeks; it is not the window you average over. Where fewer than 52 paid weeks turn up inside the bound, reg 16(3)(f)(ii) makes the divisor the number of weeks actually found rather than 52.

This is the correction the holiday pay calculator exists to make: it assembles the reference period week by week from the most recent complete week, skips and counts weeks with no remuneration payable, and stops at 52 paid weeks — or at the 104-week bound if a zero-pay week made that bound apply. A week paid statutory sick pay or holiday pay is a paid week, not a zero-pay week. Note what the tool does not do: it prices leave rather than computing entitlement quantity, it prices statutory leave up to 5.6 weeks only, so contractual leave beyond that is unpriced, and it assumes one worker classification for the whole leave year.

gov.uk’s guidance on this calculation is published at Calculating holiday pay for workers without fixed hours or pay. The older /guidance/ path for the same title no longer resolves, so update any bookmark that still points at it.

Can you pay rolled-up holiday pay instead?

For reg 15B leave, yes. Reg 16A(1) applies “in relation to pay due to a worker under regulation 16(1) in respect of leave to which the worker is entitled under regulation 15B”, and reg 16A(2) provides that “such holiday pay may be paid by way of a 12.07% uplift to the worker’s remuneration for work done.”

For anyone else, reg 16A does not reach. It is drafted by reference to reg 15B leave, so a regular-hours worker’s reg 13 or reg 13A leave is outside it, and a 12.07% uplift on their pay is not authorised by this regulation.

Two obligations travel with the choice. Regs 16A(4) to (6) deal with a rolled-up worker who goes on sick or statutory leave: for each pay period of that leave they must instead be paid the average holiday pay they received per pay period across a 52-week relevant period before the leave began, or a shorter period where they have been employed for less. And reg 16A(7) requires the itemised pay statement to show the amount of holiday pay paid in that period — a payslip-disclosure duty that is easy to miss when the uplift is folded into a single gross figure.

How does an irregular-hours worker accrue leave while they are off sick?

Under reg 15C, not under the ordinary 12.07%-of-hours-worked rule — there are no hours worked to apply it to. Reg 15C(2) sets three steps: “Step 1 Calculate the average number of hours per week that the worker worked during the relevant period before the worker started the sick leave or statutory leave. Step 2 Calculate 12.07% of the number of hours arrived at under Step 1 to find the number of hours of annual leave that the worker accrues during each week of the sick leave or statutory leave. Step 3 Multiply that number of hours by the number of weeks in a pay period for which the worker is taking sick leave or statutory leave…”

The relevant period under reg 15C(3) is “the period of 52 weeks ending with the day before the day on which the worker started the sick leave or statutory leave”, or a shorter period where the worker has been employed for less than 52 complete weeks. Reg 15C(4) discounts weeks in which the worker was on sick or statutory leave for any amount of time, while counting weeks in which zero hours were worked; reg 15C(5) backfills the discounted weeks with earlier ones “so as to bring the number of weeks to 52 (or as close to 52 as possible)”; and reg 15C(6) bounds that backfill at “the period of 104 weeks ending” with the calculation date’s week.

That 104-week bound belongs to reg 15C and to accrual. It is not the reg 16(3)(f) look-back, which belongs to pay and triggers on a week with no remuneration payable. Different provisions, different triggers, and one of the easiest pairs in the WTR to run together by accident.

What do employers most often get wrong about irregular-hours holiday?

1. Applying 5.6 weeks to a zero-hours worker. Reg 15B displaces the ordinary entitlement entirely for leave years from 1 April 2024, so there is nothing to pro-rate.
2. Assuming 12.07% covers every variable-hours worker. It applies only to workers who meet the reg 15B definitions. Applying it more widely under-states what an ordinary part-timer is owed.
3. Treating 104 weeks as the reference window. It is a conditional bound under reg 16(3)(f), engaged only where a week had no remuneration payable at all.
4. Excluding commission and regular overtime from a week’s pay. Reg 16(3ZA) requires both to be included for regs 13 and 15B leave.
5. Rolling up holiday pay for workers who are not reg 15B workers. Reg 16A does not reach them.
6. Confusing reg 15C’s 104-week backfill bound with reg 16(3)(f)’s look-back. The first governs accrual during sick leave, the second governs pay. Different provisions, different triggers.
7. Forgetting reg 16A(7). Where holiday pay is rolled up, the itemised pay statement must show the holiday pay paid in the period.

How does Taito.ai help with holiday accrual and pay?

Every rule above needs the same four inputs — worker classification, hours worked per pay period, pay per week including the reg 16(3ZA) components, and absence history — and in most small organisations those four live in a rota tool, a payroll export, a contract and somebody’s inbox. That is why an accrual balance for an irregular-hours worker tends to be reconstructed from scratch each time somebody asks for leave. Taito.ai is a people operations system that holds working patterns, absence and the employee record together, so accrual accumulates as the pay periods close rather than being rebuilt on request.

Taito.ai is not legal advice and does not track statutory change for you. The WTR will be amended again, and keeping up with that stays with the employer. What the system does is apply the classification and the accrual rule you have set to every worker consistently, every pay period, so the balance is already right when somebody asks for it.

Price a specific period of leave with the holiday pay calculator, check the holiday particular in your written statement of employment particulars is precise enough for a reg 15B worker, and see the companion guides to the 48-hour opt-out — the same instrument, a different set of provisions — and to the April 2026 statutory sick pay changes. Every UK guide, calculator and deadline we publish is indexed on UK employment compliance.