Nif Validation
Número De Identificação Fiscal or NIF, is the nine digit number which is used to identify a tax paying entity in Portugal. Any NIF can be validated using the mod 11 algorithm with one twist. I will describe what that twist is and how it affects validating a NIF. When you buy anything in Portugal, in person or online, you give your NIF. This includes everything from the 100€ you spend on your mall haul, to the 2€ you spend on an espresso and a pastel de nata....