I finally got a NIF number out! So what's the NIF anyway?  NIF is basically an income tax number and it's tied to every economic activity you do here in Portugal. From economic ID in Portugal.You will need it for almost everything in Portugal, whether it is wages from work, purchasing a property, buying a car, signing a lease, etc. Even the supermarket will ask you for the NIF number... Keep reading what NIF is and how do you get something like that out?