Employers do not need to pay employees who are on strike (that is, refusing to work at all) for the periods during which they are not working. In Hartley and others v King Edward VI College, the Supreme Court considered whether an employer was entitled to deduct 1/260th of annual salary (one working day's pay) rather than 1/365th (one calendar day's pay), when its employees went on a one-day strike.

The Supreme Court decided that the most sensible approach was, in the absence of an agreement to the contrary, to treat each day on strike as 1/365th of annual salary. This is because teachers’ monthly payments are made every month, even when they are on holiday, and the work carried out by them is (in reality) spread throughout the year. Their pay is not limited to periods when they are carrying out directed work in the classroom Monday to Friday, but includes preparatory work and their other duties such as working in the evenings and at weekends.

This case also begs the question as to what is the correct calculation of a day’s pay when similar employees are absent for other reasons, for example, holiday. The settled position for a person who works full-time (260 working days in the year, based on a five day week), is 1/260th of annual salary. This aligns with the position under the Working Time Regulations 1998. However, given this new Supreme Court decision, in the absence of an agreement to the contrary, is it safe for 1/365th to be applied to pay in lieu of accrued but untaken holiday on termination of employment? Arguably 1/365th can now be applied for permanent employees who work outside core contractual hours in order to perform their job role. Always go by what the employment contracts states, but if this is not specific on the issue, employers may not have to use 1/260th for the calculation of a day’s pay on termination. Until this question is directly answered by the courts, then a doubt about the correct method of calculation persists.