By law, as an employer, you can only reject a request if it's for one or more of the following business reasons:-
- It will cost your business too much
- You cannot reorganise the work among other staff
- You cannot recruit more staff
- There will be a negative effect on quality of work
- There will be a negative effect on the business's ability to meet customer demand
- There will be a negative effect on performance
- There's not enough work for your employee to do when they've requested to work
- There are planned changes to the business, for example, you intend to reorganise or change the business and think the request will not fit with these plans.
Find out more on ACAS's website.