Until recently, all those who were non-resident in Portugal, and from outside the EU or EEE, were required to have a fiscal representative. Post Brexit, this affected many British citizens who had a NIF (taxpayer number) in Portugal.
There is a cost to maintain a fiscal representative, and for those that had no regular activity in Portugal it seemed illogical that they were obliged to maintain this.
The thinking behind this was the presumption that it would be difficult for the Portuguese tax authority (finanças) to contact non-residents who were outside of the EU/EEE. Non-residents within the EU/EEE are allowed to register their home address (outside of Portugal) with finanças, and all necessary correspondence is sent to that address.
A recent clarification has been issued (see link below to download the full details "oficiocirculado900542022") that confirms the tax authorities stance has altered. Non-residents with a NIF are now divided into three categories, with different requirements for each.
This is good news and simplifies matters for many non-residents.
Although many people no longer need a fiscal representative, this also means that the tax authority will not be able to easily contact you. In the unlikely event that there is an issue with your tax affairs in Portugal, then you can end up in debt without realising this. We recommend that you always obtain your password and username for the finanças portal, and that way you can always check on your tax affairs.