If I am completing the self-certification form on behalf of an Entity, but do not know which classification I am, where can I find this out?

Every Entity will qualify for one of the four classification categories listed on the self-certification form even if it may not be immediately obvious which classification of entity type is relevant.   These are the four classifications specified by HMRC, and more information on each classification can be found by navigating to the Automatic Exchange of Financial Information page on the HMRC website.