Your legal rights
From day one of employment, every employee in the UK has the legal right to request flexible working. This was extended from the previous requirement of 26 weeks' service by the Employment Relations (Flexible Working) Act 2023.
You can make two statutory flexible working requests per year. Your employer must deal with your request in a "reasonable manner" and respond within two months. They can only refuse on specific business grounds set out in law.
The eight permissible grounds for refusal are: burden of additional costs, inability to reorganise work among existing staff, inability to recruit additional staff, detrimental impact on quality or performance, detrimental effect on ability to meet customer demand, insufficient work during the periods you propose to work, planned structural changes, or any other grounds that the Secretary of State may specify.
How to frame your request
A strong flexible working request focuses on the business case, not the personal reason. Your employer already knows you have a child — what they need to understand is how the arrangement will work operationally.
Be specific. "I'd like to work flexibly" is too vague. Specify exactly what you want: compressed hours (e.g., full-time hours over 4 days), part-time (e.g., 3 or 4 days), hybrid working (e.g., 2 days in office), adjusted hours (e.g., 8am–4pm instead of 9–5), or a combination.
Address their concerns before they raise them. How will you handle handovers? What happens on your non-working days? How will clients be managed? Showing that you have thought through the operational detail makes it much harder to refuse.
Propose a trial period. Suggesting a 3-month trial reduces the perceived risk for your employer and gives you both an exit if it does not work.
Put it in writing. A statutory flexible working request must be made in writing. Include the date, the change you want, when you want it to start, what impact you think it will have on the business, and how that impact could be managed. Use our Negotiate tool to help build your request.
If they say no
Ask for the reason in writing. Your employer must give one of the eight statutory grounds. If their reason does not fit any of these, or if they did not consult with you, the refusal may be unlawful.
Appeal informally first. Ask for a meeting to discuss the decision. Sometimes a modified proposal (e.g., 4 days instead of 3) can find middle ground.
Consider mediation. ACAS early conciliation is free and can help resolve disputes without going to tribunal.
Know your escalation options. If you believe the refusal is discriminatory (for example, if male colleagues have been granted flexible working), you may have a claim under the Equality Act 2010. Speak to a solicitor or contact Citizens Advice for free guidance.