Employers might want to do this for a number of reasons, for example:
So can they do that? The answer is yes.
The Working Time Regulations 1998 regulation 15 makes it clear that an employer can insist on an employee taking annual leave on particular dates, as long as they give twice the number of days’ notice that they want the employee to take as holiday. So, for example, an employer needs to give two weeks’ notice to require their employee to take one week’s annual leave.
In practice this means an employer can furlough the employee for three weeks and tell them at the start that the third week is annual leave. By definition, this then means they’ve given the required two weeks’ notice of the one week’s annual leave.