The Statutory Limit
Under Regulation 4 of the Working Time Regulations 1998 (WTR 1998), adult workers in the United Kingdom must not work more than an average of 48 hours per week. This maximum weekly limit is derived from Article 6 of Directive 2003/88/EC and applies across the employer's entire workforce, irrespective of whether staff are salaried or paid on an hourly basis.
The 48-hour ceiling is calculated as an average over a rolling standard reference period of 17 weeks. In specific sectors or where agreed via a relevant workforce or collective agreement, this reference period may be extended up to a maximum of 26 or 52 weeks. For young workers (those over the compulsory school age but under 18), stricter non-averaging limits apply: a maximum of 8 hours per day and 40 hours per week (Regulation 5A).
Individual Opt-Out Agreements
Under Regulation 5 WTR 1998, an individual adult worker may voluntarily agree in writing to opt out of the 48-hour average weekly limit. Key legal requirements for a valid opt-out include:
- The agreement must be voluntary, written, and signed by the worker.
- Employers must not subject a worker to any detriment or dismissal for refusing to sign or for choosing to cancel an opt-out (under Sections 45A and 101A of the Employment Rights Act 1996).
- The worker has the statutory right to cancel the opt-out agreement at any time by giving written notice — typically seven days, or up to three months if specified in the opt-out agreement.
What Counts as Working Time
Under Regulation 2(1) WTR 1998, working time is defined as any period during which a worker is working, at the employer's disposal, and carrying out their activities or duties, as well as any period during which they are receiving relevant training.
- Included: Core working hours, required overtime, setup and hand-over time, travel time between different client assignments during the working day, and on-call or standby time spent at the workplace where physical presence is required.
- Excluded: Standard daily home-to-work commuting, statutory rest breaks (such as the mandatory 20-minute uninterrupted rest break for shifts over 6 hours under Regulation 12), and daily or weekly rest periods.
Where an individual works for more than one employer, the aggregate hours worked across all employments must be factored in to ensure the combined total does not breach statutory maximums or health and safety obligations.
Proof and Record-Keeping Obligations
Under Regulation 9 of the Working Time Regulations 1998 and relevant case law (including ECJ ruling C-55/18 CCOO), employers are under a positive legal duty to maintain adequate, objective, and accessible records. These records must demonstrate that:
- The 48-hour average weekly limit is not exceeded for non-opted-out workers.
- Up-to-date registers of all workers who have signed valid opt-out agreements are maintained.
- Statutory rest entitlements (11 consecutive hours of daily rest and 24 consecutive hours of weekly rest) and night work limits are rigorously respected.
Because compliance is assessed over rolling 17-week reference periods, employers cannot rely on ad-hoc spot checks. A continuous, automated digital time tracking system is essential to evidence compliance, monitor average hours, and mitigate liability before an Employment Tribunal or the Health and Safety Executive (HSE).
- Updated on