Other documents required: Residence Permit or Application:
Used vehicles (minimum 6 months ownership and use) may enter under temporary duty free status with annual renewals. Subject to taxes and will require some modifications. Documents required are invoice, title, and registration.
Requires health/vaccination certificate, dated less than 12 months for dogs and cats older than 3 months.
Therefore, when you arrive in Spain your belongings will pass through customs. You will get tax 16% (IVA) on the total value of the goods (it may be based on how much you insured the goods for). If one of you is a Spanish citizen, you can avoid that tax in doing everything regarding the move on the behalf of that person (and that person should also do the baja de residencia in the originating country).