The Spanish law different form other European countries states that any resident in Spain should pay his taxes on his vessel.
But there are several different cases:
 For a new boat the tax has to be paid, stating that the vessel will not sail under the Spanish boat registration.
 If the boat is on the 6a list and no taxes have been paid due to tax exemption on this vessel, the tax would have to be paid when changing to a foreign boat registration.
 If the boat was registered under the Spanish boat registration and taxes were paid , it is very important to keep the documents as this tax only has to be paid once and you need the documents to prove it.
 If the Boat was registered under the Spanish boat registration before the Impuesto de matriculacion was established, the tax department considers the tax paid. Frequently Asked Questions