What is the maximum number of working hours an adult worker can work?

Under the Working Time Regulations 1998 (SI 1998/1833), an adult worker has the right to refuse to work more than an average of 48 hours a week, calculated over a reference period of 17 consecutive weeks, subject to certain exemptions. The 17-week period may be increased to 26 weeks for workers whose work keeps them away from home for long periods and for some other groups of workers. The 17-week period may be extended to up to 52 weeks under the terms of a collective agreement or workforce agreement that applies to particular workers or groups of workers.

Adult workers can opt out of the maximum 48-hour week by entering a written agreement with their employer.