You need to reply to a request for personal information unless an exemption applies.
One of the main rights which the Data Protection Act gives to individuals is the right of access to their personal information. An individual can send you a subject access request requiring you to tell them about the personal information you hold about them, and to provide them with a copy of that information. In most cases you must respond to a valid subject access request within 40 calendar days of receiving it.
Guidance for data controllers
We have guidance on subject access requests for some data controllers across different sectors and topics.