Hello David

Usually, you apply for the electronic criminal records certificate via the link the Ministry of justice provides for that purpose: https://sede.mjusticia.gob.es/cs/Sat...o-antecedentes, and then file it along with the nationality application.

Also, you can just tick the box that appears on the Spanish nationality application form whereby you allow the competent authorities to check the Spanish Registry of Convicts and Defaulters.

Regards,