Can your tax representative and your tax preparer be different people?

[tommigun (Tommy Gunn)]

That is not a correct understanding.
Look up other threads for conclusive discussion on the requirements for tax rep, e.g.:

Portuguese tax representation no longer required for non-EU residents

My point is that none of the official announcements make reference to the nationality of the taxable person, only to their residence. So whatever you received from the NIFOnline regarding ‘only Portuguese nationals’ must be either incorrect or wrongly attributed in this context. The determining factor for the tax rep obligation is your ‘economic activity’, which is described further in the cryptic language of AT’s official announcement from Jul 20, 2022 (see section 1, paragraph 5): I persona…

In short, tax rep is mandatory if you are ‘economically active’ in Portugal while being non-resident. And no, owning a house and/or a car in Portugal does not count as ‘economically active’. Renting out a house does count though obviously.