This from Fuster and Associates:

NEGATIVE CERTIFICATION OF RESIDENCY
“Article 2 of Royal Decree 1816/1991, dated December 20, regarding Economic Transactions with Foreign Entities, reads that the status of non-resident must be accredited by foreign individuals by means of negative certification of residency from the Spanish Ministry of Internal Affairs issued no earlier than two months previously.”

Financial entities send letters reminding their non-resident clients that, in order for their non-resident account to be maintained, they are required to present this document to their bank every two years. Some banks send a letter to their clients before the period of 2 years expires for them to sign an authorisation form enabling the entity to contact the Spanish Directorate General of Police and request said certificate (subsequent to charging the corresponding fees to the client’s account). Others are directly requesting that the client obtain the certificate themselves, informing them that they wi ll be obliged to freeze their accounts if the certification is not presented within the deadline.

Until now, the first time (when the account is opened), the client obtains the certificate and the bank renewed it every two years. From now on, it seems that some banks are reversing the trend and leaving the responsibility in the hands of their clients.

The law seems to leave the responsibility in the hands of the non-resident individual, not the financial entities.