How to Apply for a NISS in Portugal: A Practical Guide for Foreigners and Portuguese Citizens Without a Citizen Card

If you are moving to Portugal to work, study, or settle, one of the first administrative steps you will face is obtaining your NISS – the Número de Identificação da Segurança Social (Social Security Identification Number). This number is essential for employment, self-employment, social benefits, and contributions to the Portuguese social security system.

In this article, I will provide a step-by-step guide to requesting a NISS, based on the latest official information from the Portuguese Social Security Institute (Instituto da Segurança Social, I.P.). This guide applies both to foreign citizens and to Portuguese nationals who are not required to hold a Citizen Card (for example, those with a lifetime Identity Card).

What is the NISS?

The NISS is your unique identification number within the Portuguese social security system. It links you to your contributions, benefits, and social rights. With a NISS, you can:

Work legally in Portugal (whether employed or self-employed);
Contribute to social security (mandatory for most workers);
Register for certain state benefits (such as family allowance or unemployment support);
Access voluntary social security schemes.

Without a NISS, you cannot be formally registered in the Portuguese labour system.

Who Needs to Apply?

You must apply for a NISS if you fall into one of the following categories:

Portuguese citizens without a Citizen Card (e.g. those with an old lifetime Identity Card);
Foreign citizens (EU/EEA, Swiss, or third-country nationals);
Legal representatives applying on behalf of another person (such as parents or guardians);
Employers applying on behalf of new employees.

Conditions for Applying

You can request a NISS if there is a valid link to social security, such as:

Having an employment contract in Portugal;
Registering as self-employed (freelancer);
Being a member of a company’s statutory body (e.g. director);
Enrolling in the Voluntary Social Security scheme;
Needing to access social support or benefits.

In most cases, the NISS is requested when you start working or set up as a freelancer.

How to Apply for a NISS

1. Where to Apply

You can apply:

Online through the official Social Security website (www.seg-social.pt) under Help > NISS > Request for NISS;
In person at a local Social Security office (Serviços de Atendimento da Segurança Social);
Through an employer, if they are hiring you for the first time in Portugal.

Note: If the request is made by the employer, it is only for the purpose of attributing the NISS. The employer must then separately inform Social Security that the employee has started work.

2. Required Documents

The documents depend on your nationality and status.

For Portuguese Citizens without Citizen Card:

Valid Identity Card.

For Foreign Citizens from EU/EEA or Switzerland:

National ID card, or
Passport, or
Residence card.

For Foreign Citizens from Third Countries (non-EU/EEA/Switzerland):

Passport, or
Residence Permit (temporary or permanent).

For Citizens with International Protection (excluding temporary protection for Ukraine):

Proof of refugee or subsidiary protection status (e.g. Provisional Residence Authorization, refugee residence card, or official declarations of protection).

3. Proof of Purpose (Why You Need a NISS)

Since the NISS must be linked to a social security relationship, you will usually need to provide supporting documents such as:

Employment Contract (translated into Portuguese if necessary);
Proof of Self-Employment (certificate of activity opening and invoices);
Company registration certificate (for company directors);
Proof of voluntary social security enrollment;
Proof of entitlement to social benefits (e.g. school enrollment requiring social security number for child allowance).

4. Additional Documentation (Foreign Nationals)

For third-country nationals, one of the following may also be required:

Residence visa (for work, study, digital nomad, family reunification, etc.);
Temporary stay visa (e.g. seasonal work);
Digital Nomad Visa (introduced in 2022);
Work-seeking visa (in which case, Social Security may request a statement from AIMA – the Agency for Integration, Migration and Asylum – justifying the need for a NISS).

5. Collection of the NISS

Once assigned, the NISS must be collected in person at the Social Security office. You must present:

A valid identification document (passport, residence permit, or ID card).

Alternatively, the NISS may be collected by:

A lawyer with professional ID and power of attorney;
A third party with an original power of attorney or an official authorization form (PA 12), plus valid ID.

The official notification letter will be sent by registered mail to the address you indicated in your application.

Applying for a Combined Request: NISS, NIF, and NNU

Since 2022, foreigners without a Portuguese Citizen Card can apply for three essential numbers at once:

NISS (Social Security Number);
NIF (Tax Identification Number);
NNU (National Health Service Number).

Conditions

You can apply jointly if you:

Already applied for or obtained a Residence Permit;
Hold EU nationality;
Have applied for international protection or refugee status.

Where to Apply

This combined request can be made at selected Espaços Cidadão (Citizen Shops) in Lisbon, Cascais, Braga, Lagos, Setúbal, Oeiras, Loures, Olhão, and Porto.

How to Apply

You must authenticate yourself using:

Digital Mobile Key (Chave Móvel Digital – CMD), or
European eIDAS authentication system.

If you do not yet have CMD, you can activate it during the application process with your passport.

Exceptional Cases

There are situations where applicants cannot present all required documents. In these cases, Social Security may accept alternative documents, such as:

AIMA declaration (when a residence permit depends on having a NISS);
Proof of work (for cross-border workers who live abroad but work in Portugal);
Guardianship or parental responsibility documents (for children applying for family benefits).

After Receiving Your NISS

Once you have your NISS, you can:

Register as self-employed with Social Security;
Be officially declared by your employer as an employee;
Access state benefits (such as family allowance, unemployment support, or pensions);
Contribute voluntarily to Social Security if you are not otherwise covered.

Remember: the NISS is permanent. It will follow you throughout your professional and personal life in Portugal.

Practical Tips for Foreigners

Apply early: If you are moving for work, ensure the process is started before your first working day.
Keep translations: Contracts or official documents in foreign languages may need to be translated into Portuguese.
Check with AIMA: Some residence permits require you to have a NISS in advance.
Save your documents: Once assigned, your NISS letter is an important document. Keep both physical and digital copies.

Useful Contacts

Social Security Helpline:
+351 210 545 400 | +351 300 502 502 (weekdays 9:00–18:00)
Booking Line:
+351 210 548 888 | +351 300 088 888
Website: www.seg-social.pt

Conclusion

The NISS is one of the cornerstones of integration in Portugal. Without it, you cannot work, pay social contributions, or receive social benefits. While the process may seem bureaucratic, the Portuguese authorities have been simplifying it, even allowing combined applications for NISS, NIF, and NNU.

If you are an expatriate, freelancer, or new resident in Portugal, obtaining your NISS should be at the top of your relocation checklist. With the right documents and preparation, the process is straightforward and ensures that you are fully integrated into the Portuguese system.

How to Apply for a NISS in Portugal