The purpose of this measure (although a detailed explanation has not yet been provided by the authorities) appears to be to avoid VAT taxation under the special location rule in Spanish territories that already have their own indirect tax that is similar to VAT (e.g., the IGIC in the case of the Canary Islands and the IPSI in Ceuta and Melilla). This would result in a return to rules similar to those in force prior to 2014.
Source: Deloitte