The NISS ('Número de Identificação da Segurança Social' or Social Security Identification Number) is an 11-number that registers you in the Portuguese Social Security governmental services, allowing you to use its benefits and contribute as a tax.

NISS is a permanent document and doesn't have an expiration date.

It is an essential document if you intend to work for or open a Portuguese company, as it is through this ID number (along with the NIF) that companies shall inform governmental authorities about their fiscal obligations (such as who is being hired and the taxes to be paid).

If you don't plan to work for or open a Portuguese company, you won't need to apply for a NISS Portugal.

However if you intend to move with minors, we highly recommend you apply for one, as some Portuguese services, such as public healthcare, are provided for them according to parents or legal guardian NISS ownership and obligations.

The NISS allows you to use benefits from the government, such as unemployment subsidies, maternity and paternity leave, and financial support for low-income families.