The NIF (Número de Identificação Fiscal) is your Portuguese tax number. You need it for almost everything: renting or buying a home, opening a bank account, signing an employment contract, setting up utilities or starting a business. It is usually the first step for anyone moving to Portugal, and you can get it before you arrive.
Do you need a tax representative?
It depends on where you live. With an address in the European Union or the European Economic Area, you don’t need one. If you live elsewhere, for example in the UK, the US or Brazil, the Tax Authority generally asks you to name a tax representative in Portugal when you request the NIF. If you have no tax obligations in Portugal, you can later drop the representative by activating electronic notifications on the Portal das Finanças.
How the process works
You can request the NIF in person at a tax office (Serviço de Finanças), with your passport and proof of address, or through a representative with a power of attorney, without travelling. Once you have it, ask for your password for the Portal das Finanças: it is how you will deal with the Tax Authority from then on.
When you become resident
When you move, update your address with the Tax Authority to your Portuguese one. Your status changes from non-resident to resident, which changes how you are taxed and counts for the deadlines of regimes such as IFICI. It is worth getting the timing right.