Reference Period in Working Time Regulations

Key Points

Working Time Regulations 1998 (SI 1998/1833) reg 4 is entitled "Maximum weekly working time".


"Reference period" is the expression used in the Working Time Regulations 1998 (WT regs 1998, reg 4) to define the period over which the number of working hours done by a worker must be averaged for the purpose of calculating whether the maximum permitted for each seven days has been exceeded .

Under proposals put forward by the EC in September 2004, Member States were to be allowed to extend the standard reference period for calculating the average working week of 48 hours from the current 4 months/17 weeks (ie the maximum period permitted by EC Working Time Directive 2003/88/EC art 16) to up to 1 year "provided they consult the two sides of industry". After much to-ing and fro-ing this along with other proposals was rejected in April 2009.

1. Normal position (WT regs 1998, reg 4(3)(b)).

The normal reference period is any period of 17 weeks in the course of the worker's employment. There are some cases in which a longer reference period is used (see below) but in the case of a night worker the reference period is always 17 weeks and cannot be extended.

The start date for successive reference periods can be specified in a relevant agreement.

The regulations provide for holidays, sick leave, maternity, paternity, adoption or parental leave and any period in respect of which an opt-out agreement was in force to be taken into account. However if this results in any days being excluded then the 17 week reference period must be extended by a number of days equal to the number of excluded days (in other words if there were any any excluded days then hours worked in the same number of days immediately after the 17 weeks must be added to the number of hours worked during the basic 17 weeks). This is the effect of WT regs 1998, reg 4(6) and (7) as amended by the Working Time Regulations 1999 reg 3 and Working Time (Amendment) Regulations 2002, SI 2002/3128 reg 5.

2. New staff (WT regs 1998, reg 4(4)).

The reference period is the period elapsed since the worker started work for his employer.

3. Special categories of worker (WT regs 1998, reg 4(5)).

For certain categories of worker the reference period is increased to 26 weeks. The categories concerned include those who live far from their workplace, those engaged in "security and surveillance activities requiring a permanent presence" and notably those engaged in activities which "involve the need for continuity of service or production" - the regulations give examples such as hospital staff, farm workers, workers involved in gas, water and electricity production and dock and airport workers (WT regs 1998, reg 21).

4. Objective or technical reasons (WT regs 1998, reg 23).

Subject to a maximum of 52 weeks, a collective agreement or a workforce agreement can specify a some other reference period than 17 weeks if the 17 week period noted above is inappropriate "for objective or technical reasons or reasons concerning the organization of work". This does NOT apply in respect of night work by a night worker.