This information only applies in Barcelona.The paperwork process might vary significantly between cities. If you are reading this and intend to complete registration elsewhere, always check the local manners in advance. Alternatively, if you wish to receive your NIE ahead of time, you can apply for it at the Spanish Consulate in your country. Only certain consulates process NIE applications. So it is recommended that you contact the consulate first. Also be aware that processing the NIE at a Spanish consulate takes much longer.

NIE

Foreigners that come to Spain for economic, professional or social reasons can solicit an NIE from the Police Department. In the case of a foreigner not being in Spain at the moment of soliciting the NIE, the process can be carried out through the Foreign Commission Service or through Spanish Consulate offices located in foreign countries. Individuals must obtain an NIE within three months of entry in Spain.

The NIE Number is issued on a card, with the recipient’s full name (as written on the passport used during the application process), place of birth, nationality, and the number itself, along with a stamp and signature provided by the National Police.

To do this, you need to apply personally at the Foreign Affairs section (Extranjería) of the National Police station (Comisaría) on Carrer de Balmes. If you live outside Barcelona, you need to go to the designated National Police Station in your area. 

OTHER PAPERWORK

After the registration, you have completed the indispensable, but there are still many other things to pay attention to.
Spanish Social Security Number (Número de la Seguridad Social) EU NATIONALS

In order to participate in the Spanish social security system, you have to pay a contribution every month. The payment should be made by the company that has contracted.

This contribution usually entitles you to retirement and unemployment benefits, sick pay, maternity pay and free healthcare. The amount of retirement or unemployment benefits will depend on the level of the contributions you make during your time in Spain. Once you take a job in Spain your employer is required to register you in the social security system and to deduct any contributions payable by you from your wages.

However, you will have to apply for the number yourself. In order to obtain a Social Security number, you have to go to the nearest Social Security office with your NIE and your ID card or passport. There are several around the city. 

More information (in Spanish).

City Council Registration (Empadronamiento)

Getting “empadronado” means to register at the municipality you live in (not be confused with the residency). Local registration makes you an official member of the municipality and provides you with many benefits on a local level: personal doctor at the public hospital, right to vote, right to sign your children up for a local school etc. 

You can achieve local registration at the City Council (Ajuntament) or Administrative Office of your neighborhood (Junta Municipal Del Distrito). You need to bring your passport, NIE and some kind of verification that you are living in the area (rental contract or signed document from your landlord). 

The first document they give to you (volante de empadronamiento) is free but to obtain an official certificado de empadronamiento, you may or may not have to pay a fee, depending on where you live. In most cases, the volante is all you’ll need for official procedures (trámites) when working with the local bureaucracy. The official certificado is generally only needed as required by national or foreign bodies.

 

http://extranjeros.empleo.gob.es/es/ModelosSolicitudes/Mod_solicitudes2/18-Certificado_Residencia_comunitaria_EN.pdf