How should I go about making a request for flexible working?

Acas has put together a Code of Practice for employers on handling requests to work flexibly in a reasonable manner, plus guidance which includes some worked examples. You can find these documents on the Acas website. 

Your employer is not obliged to agree to your request, but they must deal with your request in a 'reasonable manner', and can only reject it for one of the specified business reasons. If your employer plans to reject all or part of your request, they must consult with you first.

It is sensible to consider how you can demonstrate that none of these reasons apply, or how you can mitigate any potential problems. Before making a formal request, it is a good idea to think about whether you might be better starting off by making an informal approach to your line manager – especially if, for example, your need for flexibility is temporary (say, to respond to bereavement or to do short-term study). Speak to your rep about what sort of approach is best for you. 

According to the Acas Code of Practice, a formal request should contain: 

• the date of your application, the change to working conditions you would like and when you would like it to come into effect; 
• a statement that you are making a statutory request; and 
• a statement explaining if and when you made any previous application for flexible working.  

Your employer should have a policy in place to explain how flexible working requests are to be handled.

Remember that any change will be permanent unless you agree otherwise, so if you would like to negotiate a temporary change, make this clear in your request.