What is Número de Identificação da Segurança Social (NISS) in Portugal?



Modified on: Mon, 25 Aug, 2025 at 3:41 PM

The Número de Identificação da Segurança Social (NISS) is the Social Security Identification Number used in Portugal to identify individuals within the national social security system. It is issued by the Instituto da Segurança Social (Social Security Institute) and is required for anyone intending to work legally in the country.


This number enables the Portuguese government to track social security contributions and entitlements, including pensions, public healthcare access, unemployment benefits, and other statutory benefits.


Why Horizons Requires the NISS

As an Employer of Record (EOR), Horizons is required under Portuguese labor and social security law to ensure all employees engaged through our Portugal entity have a valid NISS. 


Horizons requires the NISS in order to:

  • Register the employee with Social Security, ensuring compliance with contribution requirements

  • Enable payment of statutory benefits, including sick leave, parental leave, and access to the public healthcare system

  • Complete onboarding, including payroll setup and employment contract registration

Horizons requires the NISS prior to the employee’s start date.


Who Needs a NISS?

All individuals who will be employed through Horizons in Portugal must have a valid NISS, including:

  • Portuguese citizens

  • EU/EEA nationals

  • Non-EU nationals with valid work authorization in Portugal

A NISS is mandatory regardless of contract type (permanent or fixed-term) or working hours.


How to Obtain a NISS

The NISS is issued by the Instituto da Segurança Social, and the process must be handled directly by the individual or their authorized legal representative. 


To apply, individuals will typically need to submit the following:

  • Passport or national ID card

  • Portuguese tax number (NIF)

  • Proof of legal residence or visa (for non-EU nationals)

  • Proof of address in Portugal

  • Employment contract or job offer letter

Applications are typically made in person at a local Social Security office, though some local offices may accept online or third-party submissions. Processing times can vary, so it is important to begin the application process as early as possible.


When to Provide the NISS to Horizons

Employees must provide their NISS to Horizons before onboarding can be completed. Without a valid NISS, Horizons is not legally permitted to employ the individual or process payroll under Portuguese law.

Was this article helpful?

That’s Great!

Thank you for your feedback

Sorry! We couldn't be helpful

Thank you for your feedback

Let us know how can we improve this article!

Select at least one of the reasons
CAPTCHA verification is required.

Feedback sent

We appreciate your effort and will try to fix the article



Related Articles