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How to know the Social Security affiliation number from the internet

21 mayo, 2021

The Social Security number, despite being habitually in the background, it is little less than our second DNI. It is unique, it never changes and it recognizes our inclusion in the Social Security system.

A basic identification for any Spanish citizen that allows us to be identified in our labor relations, also when we receive care in the national health system and that we will need when carrying out certain procedures with public administrations.


The Social Security number and the affiliation number are exactly the same

That is why it is important to have it on hand and, if we do not have it located, keep in mind how we can ask the administration to remind us.

Requesting our Social Security number online: step by step

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In order to be able to consult our affiliation number (NAF) online we simply have to access the Electronic Headquarters of the Social Security since https://sede.seg-social.gob.es/, access the section Citizens that we will find in the menu and then click on Reports and certificates.

In this section of the web we will see a long list of available procedures. We will have to search and click on the procedure titled as Affiliate document duplicate. The drop-down that will be displayed will inform us about the four access routes to the procedure: electronic certificate, username and password of the Social Security system, Cl @ ve system or by SMS.

We can view our Social Security number through the internet identifying ourselves by means of an electronic certificate, username and password of the Social Security system, Cl @ ve system or via SMS

How to know if you are registered in social security from the Internet

This last method, probably the most practical because we receive a text message with the information directly on our terminal, we can only use it if our mobile phone number is in the Social Security database.

In the rest of the cases, after identifying ourselves, the Electronic Headquarters of the Social Security will allow us to view and consult immediately the provisional duplicate of the identification document of the Social Security, or affiliation document in case of having carried out activities that suppose framing in some Regime of the Social Security, in which the Social Security number will appear accompanied by our name and ID number. The document can be downloaded in PDF format and / or printed.

If none of these methods works for us, we can always try to find it in payroll, Social Security documents such as work life, medical prescriptions, health cards from the public health system or by calling the Social Security telephone service.