Free tool
NISS Validator: check a Portuguese NISS number
Check whether a Portuguese NISS, Numero de Identificacao da Seguranca Social, is correctly formed. Enter the 11 digits below and the tool verifies the length, the first digit and the check digit.
The 11th box, highlighted in gold, is the check digit. You can type digit by digit or paste a full number, spaces are removed automatically.
Try an example:
Privacy: this check runs 100 percent in your browser. The number you enter is never sent, stored or shared.
What a valid result does and does not mean
A valid result means the number is correctly formed: it has the right length, a permitted first digit and a matching check digit. It does NOT prove that Seguranca Social issued the number, that it is active, or that it belongs to the person typing it. Only Seguranca Social can confirm that a number was issued and who it belongs to.
If you have lost your NISS, do not apply for a new one. The NISS is issued once for life. Recover your existing number through Seguranca Social Direta or by calling the Seguranca Social line, or contact us and we will help you recover it.