This is raw translation of the web page Mobailey quoted:-
Known as identification number of foreigners (NIE) is a personal and unique number which has identification purposes in certain proceedings with public administration. The request of the NIE is linked to legal residence in the country, so that illegal residents may not request this identification number.
Where to apply for the NIE?
We may ask the NIE on any Office of aliens or the embassies and consulates of the country where residamos depending on if we are in Spain or outside of it. In any case we will have to justify the reasons why we request the allocation of the NIE documents.
Documentation for the application of the NIE
-Fill in the following application form - download PDF
-One of the following documents: full passport, travel, or certificate of registration title
-Documentation for the justification of the reasons for the request
-If you are requesting the NIE from Spain provide proof that the person concerned is not in an irregular situation
External resources
-Location of the foreign offices in Spain - mir.es
-Official information about the NIE of the Ministry of the Interior - mir.es
This message was last edited by johnzx on 31/08/2012.