Professional Fees Subscription

I have been paying professional fees for a union for many year. I have just realised I can claim that back for the last 4 years. Can someone tell me where I can fill in previous years claims on my current tax return. I know where to put them in for 2023-24 but how do I go about claimin for the years before this? It says I have to do this through self assessment.

You will need to amend your previous year's tax return. You can do this online in your personal tax account or by submitting an amendment in writing please see the guidance here:

https://www.gov.uk/self-assessment-tax-returns/corrections