The 48-hour working week and opting out

GOV.UK states that you cannot work more than 48 hours a week on average. Because the limit is an average, a busy week can run over 48 hours as long as the longer-term figure stays under it. You can choose to work more by signing an opt-out agreement.

How the average is worked out

Average hours are calculated over a reference period, normally 17 weeks. The 17 weeks can be extended to a maximum of 52 weeks if that is agreed, for example by a trade union. Some jobs differ: GOV.UK gives 26 weeks for trainee doctors and 52 weeks for offshore oil and gas.

GOV.UK does not give a formula. Applying its averaging rule, you add up the hours worked in the reference period and divide by the number of weeks in it.

What counts as working time

GOV.UK lists these as working time:

• job-related training
• travel as part of your job, such as a sales representative’s travel
• working lunches, such as business lunches
• time spent working abroad
• paid overtime, and unpaid overtime that was requested
• on-call time at the workplace
• travel between home and work at the start and end of the day, if you have no fixed workplace

These do not count:

• on-call time away from the workplace
• breaks when no work is done, such as lunch breaks
• travel outside normal working hours
• unpaid overtime you volunteered for, such as staying late to finish a task
• paid or unpaid holiday
• travel to and from work if you have a fixed workplace

More than one job

Combined hours across jobs should not average more than 48 a week. If they do, GOV.UK says you can sign an opt-out agreement or reduce your hours.

Jobs where the limit may not apply

GOV.UK says people in some roles may have to work more than 48 hours a week on average. The list covers 24-hour staffing roles, the armed forces, emergency services and police, security and surveillance, domestic servants in private households, seafarers, sea-fishermen and workers on inland waterway vessels, and jobs where working time is not measured and you are in control.

Workers under 18 follow a separate rule. They cannot work more than 8 hours a day or 40 hours a week, and they cannot average their hours.

Opting out

You can choose to work more than 48 hours a week on average if you are over 18. The agreement must be voluntary and in writing. It can cover a set period or be open-ended, and your employer must keep a record of each opt-out.

An employer can ask you to opt out, and you cannot be sacked or treated unfairly for refusing.

GOV.UK lists the groups who cannot opt out: airline staff, workers on ships or boats, road transport workers such as delivery drivers (with an exception for drivers of vehicles under 3.5 tonnes using GB domestic drivers’ hours rules), other staff covered by EU drivers’ hours rules, such as bus conductors, and security guards on vehicles carrying high-value goods.

Cancelling an opt-out

You can cancel whenever you want, even if the opt-out is part of your contract. You must give at least 7 days’ notice, and your agreement may require up to 3 months. Your employer cannot force you to cancel.

Related rights

Daily and weekly rest are covered in rest breaks, and hours worked at night have their own rules in night work. Time away from work is covered in holiday entitlement. If an employer ignores the limit or pressures you to sign, Acas gives free advice on 0300 123 1100, and early conciliation explains the step before a tribunal claim.