There are many areas where you must use the number such as:

1.Purchase and sale of a property.

2.Inheriting Portuguese assets in a last will and testament.

3.Opening a bank account.

4.Getting loans (e.g., getting a mortgage, signing a mobile phone contract).

5.Paying taxes in Portugal.

6.Receiving an income for business/work.

7.Attending a local university.

8.Receiving social security payments.

9.Setting up telecommunications or utilities.

10.Purchase of a car, or application of a driving license.

11.Signing a mobile phone contract.

12.And most other fiscal activities.