The Organisation of Working Time Act 1997 states the maximum average working week for many employees cannot exceed 48 hours. This does not mean that a working week can never exceed 48 hours; it is the average that is important. The average may be calculated over one of the following periods:
- 4 months for most employees
- 6 months for employees working in the security industry, hospitals, prisons, gas/electricity, airport/docks, agriculture or in businesses which have peak periods at certain times of the year (such as tourism)
- 12 months where this has been agreed between the employer and the employees.