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The 48-hour opt-out: what it does and does not let an employer do

A signed 48-hour opt-out disapplies one limit and no others. Daily rest, weekly rest, rest breaks and the night-work limit all survive it. What the opt-out agreement must contain, the notice on which a worker can withdraw it, and when the 17-week reference period becomes 26 or 52 weeks — cited to the Working Time Regulations.

by Mikko Kivelä··
The 48-hour opt-out: what it does and does not let an employer do

A signed 48-hour opt-out is the most over-read document in UK working-time administration. It is a real mechanism with a real effect, but the effect is narrow: it disapplies one average, and it leaves every rest and night-work protection in the Working Time Regulations 1998 exactly where it was. This guide walks through what the opt-out reaches, what it does not, and what the agreement itself has to say.

TL;DR

  • The opt-out disapplies the average of 48 hours for each seven days and nothing else — it lives in the opening words of reg 4(1), not in a separate right.
  • Daily rest of 11 consecutive hours (reg 10(1)), weekly rest of 24 hours (reg 11(1)) and the rest break after six hours (reg 12(1)) all survive it.
  • Night workers keep a separate average of eight hours in each 24 (reg 6(1)) — a different test on a different denominator.
  • The agreement must be in writing and obtained first (reg 4(1)); a worker can withdraw it on seven days’ notice unless the agreement sets a different period, which cannot exceed three months (reg 5(2)–(3)).
  • The reference period is 17 weeks by default, 26 weeks for reg 21-excepted workers (reg 4(5)) and up to 52 weeks by collective or workforce agreement (reg 23(b)).
  • You must keep records adequate to show compliance with the 48-hour limit and retain them for two years (reg 9), plus up-to-date records of everyone who has opted out (reg 4(2)).

What does a 48-hour opt-out actually disapply?

One thing. Reg 4(1) reads: “Unless his employer has first obtained the worker’s agreement in writing to perform such work, a worker’s working time, including overtime, in any reference period which is applicable in his case shall not exceed an average of 48 hours for each seven days.”

The whole opt-out is that opening subordinate clause. Where the agreement exists, the 48-hour average does not apply to that worker; where it does not, it does. Nothing in reg 4(1) reaches any other regulation, and no other regulation is drafted to respond to a worker’s individual agreement in the way reg 4(1) is.

That matters because the working-time protections an employer is most likely to breach in practice are the rest provisions, not the average. A worker on a rolling 17-week average can sit comfortably under 48 hours and still be worked through their daily rest on a bad week.

What must the opt-out agreement contain, and how does a worker withdraw it?

The opt-out is not a free-standing reg 5 right. Reg 5(1) has been repealed and now renders in the consolidated text as an omitted subsection. What survives in reg 5 governs the form and cancellation of the agreement reg 4(1) refers to:

  • It must be in writing, and the employer must have “first obtained” it — the agreement precedes the excess hours, and a signature collected after a breach does not retrospectively cure one (reg 4(1)).
  • Reg 5(2)(a): the agreement “may either relate to a specified period or apply indefinitely”.
  • Reg 5(2)(b): “subject to any provision in the agreement for a different period of notice, [it] shall be terminable by the worker by giving not less than seven days’ notice to his employer in writing”. Seven days is therefore the default withdrawal notice, not a floor you have to write in.
  • Reg 5(3): where the agreement does set its own notice period, “the notice period provided for shall not exceed three months”.

The practical reading: an opt-out is never permanent. A worker can hand back seven days’ notice on an ordinary Tuesday, and if your rota depends on their opted-out hours you have a week to re-plan.

Reg 4(6)–(7) then set out how the average itself is computed. The formula is “A/C + B/C”, where A is the hours worked during the reference period, C is the number of weeks in it, and B is the hours worked in the days immediately after the reference period, counted until the worker has worked as many days as there were “excluded days” inside it. Excluded days are annual leave under reg 13, reg 13A or reg 15B, sick leave, maternity, paternity, adoption or parental leave, and any period in which the 48-hour limit did not apply because the worker had opted out. An excluded day is therefore not averaged away — it is made up by a later working day.

Which reference period applies — 17 weeks, 26 weeks or 52?

Three answers, and which one you get is not a matter of choice:

  • 17 weeks is the default. Reg 4(3) gives either successive 17-week periods where a relevant agreement provides for them, or otherwise any 17-week period in the course of the worker’s employment. Reg 4(4) shortens it to the period elapsed for anyone employed less than 17 weeks.
  • 26 weeks for workers excluded from certain provisions by reg 21 — the excepted activities. Reg 4(5) applies reg 4(3) and (4) to them “as if for each reference to 17 weeks there were substituted a reference to 26 weeks”.
  • Up to 52 weeks where a collective or workforce agreement substitutes a longer period, for objective or technical reasons or reasons concerning the organisation of work (reg 23(b)).

Which limits survive the opt-out?

All of them except the one. This is the table worth keeping in front of whoever administers your rotas.

Provision The limit Disapplied by an individual opt-out?
reg 4(1) Average 48 hours per seven days over the reference period Yes — this is the only thing it does
reg 6(1) Night workers: average eight hours in each 24 No
reg 10(1) Daily rest: 11 consecutive hours in each 24-hour period No
reg 11(1) Weekly rest: 24 hours in each seven-day period No
reg 12(1) Rest break where the working day exceeds six hours No
reg 23(a) — Not an opt-out: a collective or workforce agreement may modify or exclude regs 6(1) to (3) and (7), 10(1), 11(1) and (2) and 12(1)

What records must an employer keep on working time?

Two separate duties, and most employers only know about one of them.

Reg 9(1) requires an employer to “(a) keep records which are adequate to show whether the employer has complied with the limits specified in regulations 4(1), 5A(1) and 6(1) and (7) and the requirements in regulations 6A and 7(1) and (2); (b) retain such records for two years from the date on which they were made.”

Read that list literally. It covers the 48-hour average, young workers’ hours, night work and health assessments — it does not cover annual leave or holiday pay, so reg 9 is not the authority for how long to keep holiday records. Reg 9(2) leaves the manner and format entirely to you: records “may be created, maintained and kept in such manner and format as the employer reasonably thinks fit.” Reg 9(3) adds that you “need not record each worker’s daily working hours” if you can demonstrate compliance without doing so.

The second duty sits in reg 4(2), and it is specific to the opt-out. Alongside the obligation to take all reasonable steps to ensure the 48-hour limit is complied with, an employer “shall keep up-to-date records of all workers who carry out work to which it does not apply by reason of the fact that the employer has obtained the worker’s agreement”. A signed form in a drawer is not an up-to-date record of who is currently opted out — particularly once a worker has given their seven days’ notice.

What can a collective or workforce agreement change?

More than an individual agreement can, and this is the distinction to get right. Reg 23 provides that a collective agreement or a workforce agreement may “(a) modify or exclude the application of regulations 6(1) to (3) and (7), 10(1), 11(1) and (2) and 12(1), and (b) for objective or technical reasons or reasons concerning the organization of work, modify the application of regulation 4(3) and (4) by the substitution, for each reference to 17 weeks, of a different period, being a period not exceeding 52 weeks.”

So the rest and night-work provisions are not absolute — but the only instrument that reaches them is a collective or workforce agreement, and the only thing an individual signature reaches is reg 4(1).

What do employers most often get wrong about the opt-out?

  1. Treating a signed opt-out as covering rest and night work. It covers reg 4(1) and nothing else. This is the largest live exposure in the whole area, because the rest provisions are the ones a busy rota actually breaches.
  2. Citing reg 5 as the source of the opt-out right. Reg 5(1) is repealed. The mechanism is the opening clause of reg 4(1); reg 5 only governs the agreement’s form, duration and cancellation.
  3. Applying 17 weeks to reg 21-excepted workers. They get 26 weeks under reg 4(5), and using the shorter window produces the wrong average.
  4. Running the reg 4 48-hour test on night workers and stopping there. Reg 6 imposes a separate eight-hours-per-24 average. Passing one test says nothing about the other.
  5. Treating an opt-out as permanent. It is withdrawable on seven days’ notice by default, or on whatever notice the agreement specifies up to a three-month ceiling (reg 5(2)–(3)).
  6. Miscounting the reference period by including excluded days. Under reg 4(6)–(7), annual leave, sick leave, family leave and already-opted-out days do not count towards the average; each is made up by a working day from immediately after the reference period.
  7. Keeping the signed forms but not the reg 4(2) register. The duty is to hold an up-to-date record of who is opted out, which changes every time someone signs or withdraws.

How does Taito.ai help with working-time limits?

Working-time breaches are usually discovered late rather than allowed knowingly. Nobody sits down on a Tuesday afternoon to reconcile a rolling 17-week average against a rota tool, a payroll export and a folder of signed opt-out PDFs, so the average gets worked out after a complaint, an audit or a tribunal claim has already made it urgent. Taito.ai is a people operations system that holds working patterns, absence and the employee record together, so the reference-period average and the gaps between shifts sit on the same record as the opt-out status.

Taito.ai is not legal advice, and it does not track statutory change on your behalf: an amendment to the Working Time Regulations will still move a threshold, and spotting that is yours to do. Where it earns its place is in making the limit visible before it is crossed rather than after.

Working time and annual leave sit in the same instrument but pull in different directions for variable-hours staff — see the guide to holiday entitlement and holiday pay for irregular-hours workers, and check that your written statement of employment particulars actually describes the hours and days you are rostering. The other UK statutory guides, and the dated PAYE and year-end calendar, are on UK employment compliance.

Frequently asked questions

Does a 48-hour opt-out remove the rest break and daily rest requirements?
No. An opt-out obtained under regulation 4(1) of the Working Time Regulations 1998 disapplies one thing only: the average of 48 hours for each seven days. Every other limit in Part II survives it untouched. Your workers keep 11 consecutive hours of daily rest in each 24-hour period under reg 10(1), 24 hours of uninterrupted weekly rest in each seven-day period under reg 11(1), and a rest break once the working day exceeds six hours under reg 12(1). Night workers keep the separate 8-hours-per-24 average in reg 6(1). The only route that reaches those provisions is a collective or workforce agreement under reg 23(a), which may modify or exclude regs 6(1) to (3) and (7), 10(1), 11(1) and (2) and 12(1). An individual signature cannot do it, and treating one as though it can is the largest live exposure most employers carry.
What must a 48-hour opt-out agreement contain?
Start from the fact that the opt-out is not a free-standing right. Regulation 4(1) opens with the words "Unless his employer has first obtained the worker's agreement in writing to perform such work", so the agreement must be in writing and must be obtained before the limit is exceeded, not documented afterwards. Regulation 5(2) then governs its terms: the agreement "may either relate to a specified period or apply indefinitely", and, subject to any provision in the agreement for a different period of notice, it is "terminable by the worker by giving not less than seven days' notice to his employer in writing". Reg 5(3) caps that: where the agreement does set its own notice period, that period "shall not exceed three months". So seven days is the default, and three months is the outer bound on anything longer you write in.
Is the 48-hour reference period always 17 weeks?
No. Seventeen weeks is the default, not the only option. Regulation 4(3) gives you either successive 17-week periods where a relevant agreement provides for them, or otherwise any rolling 17-week period in the course of the worker's employment. Where a worker has been employed for less than 17 weeks, reg 4(4) uses the period elapsed since they started. For workers excluded from certain provisions by reg 21 — the excepted activities, such as security and surveillance work or a need for continuity of service — reg 4(5) substitutes 26 weeks for every reference to 17. And a collective or workforce agreement may, under reg 23(b), substitute a different period "not exceeding 52 weeks" for objective or technical reasons or reasons concerning the organisation of work. Applying 17 weeks to a reg 21 population understates the averaging window.
What are the working time record-keeping requirements?
Regulation 9(1) of the Working Time Regulations 1998 requires an employer to "keep records which are adequate to show whether the employer has complied with the limits specified in regulations 4(1), 5A(1) and 6(1) and (7) and the requirements in regulations 6A and 7(1) and (2)" and to "retain such records for two years from the date on which they were made". Read the list carefully: it covers the 48-hour average, young workers, night work and health assessments. Annual leave and holiday pay are not in it, so reg 9 is not the authority for how long you keep holiday records. There is a second, separate duty: reg 4(2) requires an employer to "keep up-to-date records of all workers" whose hours are uncapped because they have opted out. Reg 9(2) leaves the manner and format to you, and reg 9(3) says you need not record each worker's daily working hours if you can demonstrate compliance without doing so.
What is the maximum average night workers can work?
Night work has its own limit, and it is not the 48-hour one. Regulation 6(1) of the Working Time Regulations 1998 provides that a night worker's normal hours of work "shall not exceed an average of eight hours for each 24 hours". That is a different test on a different denominator from the reg 4(1) average of 48 hours for each seven days, and a worker can comply with one while breaching the other. An individual opt-out does not touch reg 6 at all — reg 4(1) is the only provision its opening words address. The only route to modifying or excluding reg 6(1) to (3) and (7) is a collective or workforce agreement under reg 23(a), and reg 9 requires you to keep records adequate to show you have complied with reg 6(1) regardless.