NIE (Identification number for foreigners in Spain)
Due to some changes in Spanish legislation, if you get paid in your internship you are required to apply for a NIE number and a Social Security number. Depending if you are European or non-european the process will be different.
For non EU-citizens: You can do it in the Consulate in your home country at the same time that applying for the Student VISA. Please note you will need to do it before coming to Spain. To learn more about the Student VISA click here.
For EU-citizens: You will need to make an appointment more or less one month before your arrival so that you can have it before starting in the company. Notice that you have to book your appointment one month before coming to Spain, and arrive 3-4 days before your internship starts in order to go to your appointment and get as well the social security number.
In the following link you can book your appointment: https://sede.administracionespublicas.gob.es/icpplus/citar
You just have to select the city you will be living and after that introduce your personal information. Once that you have your NIE, take it with your internship contract to the closes Social Security office nearby your house and ask for "número de la seguridad social". With this everything will be done.
To check the addresses of the NIE offices you can see it here: http://www.policia.es/documentacion/oficinas/oficinas_extran.html. In any case, when booking the appointment you will receive an address.
Concerning the social security number, you can see the offices here: http://www.seg-social.es/Internet_1/Oficinas/index.htm. Our advice is just to google "seguridad social + name of your city or neighborhood". You will find it in Google Maps.