Registration with the social security system

What do you need to know?

Registration with the social security system is an notification that must be made to the Social Security system when a work activity is to begin, either as an employee or as a self-employed individual.

The formality is compulsory and must be completed before beginning the activity.

It gives you access to the public Social Security system that offers protection against situations of illness, disability, unemployment, old age, accidents at work, maternity or loss of the family's means of support.


In the case of employees, it is the employer that is responsible for registering the worker in the general social security system.

In the case of self-employed individuals, they themselves are directly responsible for applying for registration in the special scheme for the self-employed (RETA).

Only the procedure for registering with the social security system for self-employed individuals is explained below.

Who does it apply to?

It applies to all citizens who wish to start a professional activity, whether as employees or as self-employed individuals.

What requirements must be met?

  1. Have a social security number.
  2. In the case of citizens from outside the European Union (EU), the European Economic Area (EEA) or Switzerland, you must have the relevant work permit.

How long is it valid for?

The validity is the same as the duration of the activity.

What do you need to do?

You can register with the social security system in person by going to the Provincial Office of the General Treasury of the Social Security System or a social security office (by prior appointment), or electronically over the website, if you have a digital certificate or other electronic authentication mechanism.

Only the procedure for registering with the social security system on the special scheme for self-employed individuals (RETA) will be explained below.

What steps must you follow?


Step 1. Obtain a digital certificate,  cl@ve pincl@ve permanente or provide your mobile phone number to be able to enter via SMS.

Step 2. Apply for a social security number (NUSS)

Step 3. Go to the Social Security website.

Step 4. Select the option “Alta en trabajo autónomo" (registration of self-employment) and follow the instructions.


Step 1. Apply for a social security number (NUSS)

Step 2. Arrange an appointment

Step 3. Go to a Social Security office, fill in the standard application form, attach the required documentation and register.

Who can submit the application?

All individuals who wish to begin a professional activity, as a self-employed worker or employee, must be registered with the social security system. The person responsible for applying is not the same in the case of a self-employed worker as in that of an employee. The application can be submitted by:

  • The individual himself or herself, if self-employed.
  • The employer, in the case of employees.

What documentation is needed?

To apply in person, you must submit:

  • Application form (TA.0521), signed by the person concerned.
  • Identity document (identity card for foreign nationals or passport).
  • In the case of applying for registration as a self-employed individual: documentation attesting to registration with the Tax Office.

How long does it take?

Registration with the social security system is carried out at the same time as the application. It must be prior to the start of the activity or at the latest on the same day it starts.

What does it cost?

Applying is free of charge. Afterwards, you must contribute a monthly sum, which varies depending on your job category.

Want to know more?

Body responsible for the formality

The General Treasury of the Social Security System. (The information is available in English, Catalan, Spanish and other co-official languages of the Spanish state.)

Further information?

On the Social Security website (available in English, French, Catalan, Spanish and other co-official languages of the Spanish state).

Barcelona has a public service for companies called the Business Support Office (OAE), where they will offer you personalised advice on all the strategic areas for the management and growth of your business activity.


The procedures tend to change frequently. Therefore, only what is provided by the regulations in force at the time of carrying out the procedure in question is applicable.