Under the Working Time Regulations 1998 (WTR), the 48-hour average working week is normally calculated using a 17-week reference period. This can be extended up to a maximum of 52 weeks by a collective agreement or workforce agreement, but only if there are objective or technical reasons concerning the organisation of work. An example of where such an extension might be useful is where workers are on annualised hours contracts.
A collective agreement is an agreement between the employer and an independent trade union. A workforce agreement is between an employer and the elected representatives of its employees or, in the case of small employers (i.e. those with 20 or fewer employees), the employees themselves. Workforce agreements are only allowed where there are no recognised unions.
