Can you require your staff to take annual leave over the Christmas period?
The answer is yes you can. The Working Time Regulations give staff a statutory entitlement to annual leave but the Regulations do not specify that staff can take annual leave as and when they would like to do so. If your organisation closes down over the Christmas period you can insist that time is taken as annual leave.
Of course, it would be fair and reasonable to ensure that your staff know they need to retain a number of days annual leave to cover the closure otherwise the enforced time off may revert to being unpaid leave and that may be an unpleasant surprise for some people and do little to maintain staff engagement.
Many organisations impose annual leave on their staff. For example, school staff are not allowed to take annual leave during term time. Manufacturing industries close down for a week at Christmas, a week at Easter and two weeks in August, known as Wakes Weeks. Those weeks are used by the organisation to undertake the servicing of machinery and health and safety checks whilst also ensuring that when the factory is up and running, all the staff are there to deliver the product.
Conversely you may want to keep your organisation functioning over the Christmas period but find that many of your staff have requested annual leave making it difficult for you to continue to provide a service to your customers and clients. How to manage that equitably will vary from organisation to organisation. My experience is to let staff manage the issue themselves! Put a chart on the wall stating how many staff you need in place on any given day and then invite your staff to negotiate between themselves who will take which day(s) off as annual leave.