Can an employer require employees to use their annual leave during the coronavirus outbreak?
Generally, employers can require employees to take a period of annual leave during the coronavirus (COVID-19) outbreak, provided that they give the employee the required notice. This is unless there is an agreement to the contrary (such as in the employee's contract or a collective agreement). The employer must give the employee a period of notice at least twice as long as the period of leave it requires them to take. For example, if the employer requires the employee to take one week's annual leave, it must give them at least two weeks' advance notice.
Where an employee is furloughed, it is less certain that the employer can require them to take annual leave (although the need to pay employees their normal weekly pay during a period of annual leave may mean this is an unattractive option for many employers in any event). Government guidance on Holiday entitlement and pay during coronavirus (COVID-19) states that: "If an employer requires a worker to take holiday while on furlough, the employer should consider whether any restrictions the worker is under, such as the need to socially distance or self-isolate, would prevent the worker from resting, relaxing and enjoying leisure time, which is the fundamental purpose of holiday." While case law has found that employees can be required to take annual leave at a time when they would not otherwise be working (Russell and others v Transocean International Resources Ltd and others  IRLR 149 SC), it is not clear if the same principles would apply during furlough. Therefore, the safest option for employers is not to require employees to use their annual leave during furlough.
If an employer does wish employees to use their holiday while furloughed, it should seek their agreement to this, rather than imposing a period of annual leave on them. Employees in receipt of reduced pay may be happy to take annual leave while they are furloughed, if this would be on full pay.
Employees will be able to carry over unused leave in some circumstances (see When can annual leave be carried over due to the coronavirus crisis?).