There are 8 reasons for rejecting a flexible working request. These are:-
The burden of additional costs; and/or
An inability to reorganise work among existing staff; and/or
An inability to recruit additional staff; and/or
A detrimental impact on quality of work; and/or
Detrimental effect on ability to meet customer/patient demand; and/or
Insufficient work during the proposed times; and/or
Planned structural changes to the business.
It is however advisable to be cautious in exercising the right to decline a flexible working request, as this could lead to potential indirect discrimination issues, for example where the employee is responsible for childcare. You should seek independent advice should you receive a flexible working request you cannot facilitate.