As part of the Agrément Certification process, there are ongoing obligations for the Certificate Holder and the BBA to maintain the Certificate. The BBA carries out 2 types of maintenance activity once the Certificate has been issued: factory surveillance visits and Certificate Reviews. These activities ensure the ongoing compliance of the Certificate, the production and the certified product(s).

You can read more about this in depth here: https://www.bbacerts.co.uk/2021/06/01/the-difference-between-post-certificate-surveillances-and-reviews/