It is a slow and expensive process to obtain probate if you die interstate. Your heirs will need to get your Spanish property transferred to their names; the process is much simpler if there's a Will. If there is no Will registered at the Registro de Actos de Ultima Voluntad, then in the worst case, your property will pass to the local and regional government. Current European legislation allows EU citizens to use the succession rules of their home nation when drafting a Will. Advice should be sort in order to understand any tax implications associated with drafting a Spanish Will in this way.