Below is a quick and simple checklist for paperwork in Tenerife, particularly in the light of Brexit (see the Brexit post HERE). Please also see THIS page for further detail on the documents mentioned below. I would also just make the point that a lot of confusion has been caused by the wrong names repeatedly being given for these various pieces of paperwork: below is the correct terminology and it is vital to avoid confusion given that after Brexit British citizens here will not be EU nationals in an EU country.
NIE: a white certificate bearing a number. The letters stand for Número de Identificación de Extranjero, i.e. Foreigners Identification Number. This is all the NIE is: a number used for official transactions in Spain. It has no other function.
Residencia: there is no such thing. Residencia was never a document anyway, but a system for an optional procedure to get a foreigner’s identity card. The card became known as “a residencia”. The system was abolished several years ago (2012) for EU nationals and was replaced by a compulsory registration of foreigners living in Spain.
Certificado de Registro: this is a document printed on green paper (used to be A4 size but is now credit-card sized) which is known by a range of names, including green certificate, green card, green NIE, residencia. It is, though, a registration certificate properly called a Certificado de Registro which is provided by the police to residents who comply with the legal requirement of registering with the police as a foreigner living in Spain. The document clearly states it is a Certificado de Registro and under EU law it does not need to be renewed, but those with them can apply if they want to for one that says “permanente” after they’ve been in Spain for five years, or for a card-sized one if they have an old A4 size. THE CERTIFICADO DE REGISTRO IS THE ONLY THING THAT PROVES LEGAL RESIDENCE.
Empadronamiento: this is a certificate provided by a local Ayuntamiento when someone living in a municipality signs onto the local list of residents, the “Padrón”. This is a kind of equivalent to the UK’s electoral register, compiled council by council, but unlike the UK does not convey a right to vote: for that, local residents also have to ask the council to put their name on the “census” as well as the padrón (note that we can only vote in local elections here).
Empadronamiento para viajar: this is a version of the Certificado de Empadronamiento supplied by councils to provide legal residents with the Government-subsidized travel discount. It is called various names, but most commonly “a viaje”. To enjoy the discount one needs to have a Certificado de Registro in addition to this “viaje” … because it is only legal residents who are entitled to the discount, and as said above, the only document that proves legal residence is the Certificado de Registro.