What the law limits.
- Daily rest: 11 consecutive hours in every 24 (regulation 10). A day from 8:00 to 20:00 means no return before 7:00 the next day.
- Breaks: a 20-minute break when the working day is longer than 6 hours (regulation 12).
- Weekly rest: 24 hours in every 7 days, or 48 hours in every 14 (regulation 11).
- Weekly average: 48 hours a week on average over 17 weeks, unless the worker has signed an opt-out (regulations 4 and 5). In Great Britain, a worker can agree in writing to opt out of the 48-hour average (regulation 4); they can cancel the opt-out with 7 days’ notice, or up to 3 months if the agreement says so (regulation 5).
Pros and cons for the practice.
For the person: more days off in a row and fewer journeys, in exchange for very long days. For the practice: fewer handovers to organise, but every absence leaves a 12-hour gap to cover, and the overlap between morning and afternoon teams disappears.
Test it before announcing it.
Before announcing long days to the team, build a month with them. With Djed, shift mode lets you define 12-hour days and see whether cover holds up with real leave. The Clinic plan’s “what if?” simulator compares the current month with the variant, without touching the published rota. Djed doesn’t check the 11 hours or the 48-hour average: that check stays with you.
Sources and date checked.
- Working Time Regulations 1998 (SI 1998/1833), regulations 4 to 12. Northern Ireland has its own regulations, the Working Time Regulations (Northern Ireland) 2016, with the same limits.
Texts checked on 5 October 2026. This guide is not legal advice: for your own situation, speak to your HR or employment adviser.
Where to go next.
- The other limits a 12-hour day must not break, under the Working Time Regulations: our working time guide, the reference guide of this series.
- On-call the night before a long day: our on-call guide and rest after on-call.
- If the long day runs into the night: night workers.
- On the nursing side, where shifts make it harder: vet nurses and vets on one rota.
Frequently asked questions.
Can vets work 12-hour days in the UK?
The regulations don’t cap the length of a single day directly; 11 hours’ daily rest, a 20-minute break, weekly rest and the 48-hour average set the limits.
Can a vet opt out of the 48-hour average?
Yes, in writing (regulation 4), and they can cancel the opt-out with 7 days’ notice, or up to 3 months if the agreement says so.