The notarial document is a public document executed in the presence of a notary and offering the utmost legal certainty under Spanish Law. It has powerful effects, specifically regulated by law, wich far exceed those who have a private document. The public authorities, judges and society in general at large attribute absolute credibility to the facts or declarations recorded in a public deed.

It is based on precise regulations, fulfil conditions of authenticity (confirming that the particulars recorded are true), enforceability (the agreement is put into practice without the need for further evidence) and legality (they comply with the legal provisions). Private individuals signing a notarial instrument have the guarantee that no one will be able to question its veracity.

It is a complete instrument requiring no form of confirmation or comparison, and that in itself enjoys the full effectiveness of the Law from the moment the notary authorises it. It is an enforcement instrument with evidential force as to the dates, facts and declarations it contains.

A notarial document is circulated only through paper or electronic copies; the original instrument bearing the original signatures of the executing parties is held in the protocol record of the practice of the notary who authorised it. It is subsequently transferred to the notarial archives of each College, and then to the Historical Archive. Notarial instruments are forever.