VGROUPS01800 - General principles of VAT group treatment: group treatment and divisional registration
A company that is registered as a divisional registration may not join a VAT group, as divisional registration and VAT group treatment are incompatible.
Where a company that is a divisional registration wants to join a VAT group, it must first deregister all its divisions.
Similarly, a company that is a member of a VAT group may not separately register any of its divisions whilst maintaining the rest of its activities in the group. An application for divisional registration from a company that is a member of a group must be accompanied by an application to leave the group by the date on which the divisional registration is to take effect.