Certain administrative procedures require the submission of documentary proof in the form of a certificate or an attestation.

An attestation is a declaration whereby an organisation bears witness to the existence or truth of a fact.

A certificate is a type of attestation. It is a more official document, issued by a competent authority, to attest to a fact or a right. Thus, communal administrations are authorised to issue residence certificates providing information on the applicant's place of residence, whilst certificates of nationality are issued by the Ministry of Justice (Ministère de la justice) to persons holding Luxembourgish nationality.

Other documents that are similar in purpose and effect to certificates are legal deeds for civil registry entries (deeds, for example, attesting to a birth), document authentications (certifying the origin of a document), and signature authentications (certifying the authenticity of the signatures on a document or deed).