At the end of the study
Where a project has HRA Approval you will need to tell HRA when the project has ended. If the study has been reviewed by an NHS REC you should send notification to the REC. If a project did not require REC review, you should send this notification by email to firstname.lastname@example.org including your IRAS ID and your contact information (phone and email).
For other actions when your study comes to an end there is broader guidance under the Research Community section of the HRA website.