Travel documents for minors – Spain
Minors require a valid travel document to leave Spain. In addition, if they are travelling with an identity card, instead of the passport, they must have a written authorization signed by whoever has legal custody or guardianship. This written authorization must be certified in any police station, civil guard post, court, notary or City Hall, upon presentation of the family book or birth certificate.
You can find the authorization forms:
Minors from an EU country who enter Spain with an identity card (instead of a passport) also need a written authorization as described in paragraph 1.
Contact if you need to request more information.