Letter wording: I refer to your request to take annual leave from [date] to [date]. Unfortunately, on this occasion, I must decline your request because [annual leave has already been approved for other members of staff at this time and I cannot permit anyone else to be off because of the need to maintain adequate staffing coverage/this will be a particularly busy time for the Company so annual leave cannot be taken on those dates/you have insufficient annual leave remaining in the Company's current holiday year/you are in your first year of employment and you have not yet accrued sufficient annual leave to cover those dates/[other reason]].