Gift Aid claims must be submitted to HMRC within 4 years of the end of the relevant accounting period in which the donation was received.
This means:
For most charities, this is within 4 years of the end of the tax year (6th April to 5th April) in which the donation was made.
For CASCs, CIOs and charities that are limited companies, this is within 4 years of the end of your accounting period.
Example: If a donation was made in June 2019, it must be claimed by April 2024, as it falls within the 2019–2020 tax year.