The NISS is a unique and personal number that identifies each citizen in the Portuguese Social Security system. It is essential for those who work or wish to work in Portugal, as it allows the corresponding discounts, access to entitlements such as unemployment benefits, medical leave, retirement pensions, parental leave and family allowance. It also facilitates access to the Segurança Social Direta portal, opening bank accounts and applying for loans. Any foreign or national citizen without a citizen card can apply for it. Without a NISS, you will not be able to declare your income correctly or benefit from the labor and social rights to which you are entitled.