Newcomers to Portugal soon learn that they need one particular number for a whole range of everyday transactions in the country: The NIF (Número de Identificação Fiscal), also known as Número de Contribuinte.
I got mine in 15 min. It was simple and easy. 
Yes, same! As long as you go in the morning it’s painless 
hi good morning i was thinking of applying for my NIF card as a us citizen they want a Tax represerntative that is what all sites say is that true?
Yes. US Citizen would need that to get a NIF from what I have heard. They call it a fiador, basically a guarantor. But I’m not from the US myself, so can’t say that is the case every time. The Americans I’ve met needed it.
According to the law it’s true. The Portal of Citizen Services NIF page references Decree-Law No. 14/2013 of January 28 (Decreto-Lei n.º 14/2013, de 28 de janeiro).
Article 10 states:
3-Foreign citizens who wish to enroll non-residents in accordance with tax legislation shall, at the time of their registration, submit cumulatively the following documents:
a) Civil identification document or other legally equivalent;
b) Power of attorney or mandate contract with with the tax representative;
c) Fiscal and civil identification document of the tax accountant.
In the Portuguese version ‘tax representative’ and ‘tax accountant’ are both ’ representante fiscal’, which matches what all the sites say.
According to reports, seemingly any given office tasked to provide NIFs can add requirements.
Thanks @dancebert, that’s really helpful! I’ve added a note to the article to let people know that the process I outline is relevant only to EU/EEA citizens (perhaps also Swiss?), and pointing anyone else to this thread for more info!
My research on lease requirements took me back to a NIF requirement. It’s confusing because English speakers and translation apps use different terms for what may be the same thing. Here is one law firms definition of a ‘Tax Representative’, the same term I posted earlier in the translated version of the Portuguese law: “The Tax Representative is legally responsible for receiving their fees, property taxes, inform the taxpayer of all tax obligations, and ensure that payment is made within the designated time limits.”
I found this definition of Fiador on a Portuguese site selling business and tax advice (google translate converted fiador to guarantor): “The legal status of the “guarantor” is regulated in the civil codes (and not in commercial legislation). In this regard, in general, it is said that the bond is a contract by which a person agrees with the creditor to pay for the debtor, if he does not (although the guarantor can, in the contract, waive his right to order). That is, the guarantor will respond to the creditor only if the debtor does not do so.”
I read that as a Tax Representative’s role is between Financias (AKA The Tax Man 
) and the person seeking a NIF. A Fiador is what is called in the US a co-signer. He’s responsible for the debts of the person using him as a Fiador.
I made a long post about this on one expat forum asking for feed back and links to support the feedback. Got nothing. I’m going to post it on other expat and FB forums. If and when I get results, I’ll post back here.
Let me know if you don’t get any useful results from those sources, and I’ll ask around a bit here (I just arrived in Portugal last night). 
Hi Everyone,
Just a thought … what rules apply to those who are not European citizens (originally from North America) but have who have permanent residency in other EU states like France as an example?
TBH, I’m not sure. Perhaps someone else here knows? If I find out I’ll post it here 
Hey guys! Just got more details on tax representatives for getting NIG by non-EU residents.
I’m trying to figure out what my Portuguese friend has to sign. Perhaps you know here
What for?
I’m going to Portugal this summer and would be keen to sign up for a NIF and bank account while I’m there. Do I really need a tax representative to join me on the visit to this office or not?
I got my NIF today in Portugal. I’m a US citizen living in Thailand for 8 years on a long-stay visa. I went to the local Finanças office with a Portuguese citizen who had offered to be my Financial Representative. For proof of residence in Thailand I showed a notarized translation of my Thai motorcycle license, which has my address. FWIW I noticed the agent flipped though my passport from back to front until he found the most recent yearly extension of my Thai visa. The NIF cost 10.2 Euros
Wondering how I found a local to be my Financial Rep? It was pure luck. I saw the hotel owner as I was walking down the stairs. At the same time a woman came in from the street. They’re obviously old friends. I waited. When owner saw I was waiting to him, he asked why. I asked him if he later could give me the names of any law offices / attorneys who spoke English because I need a Financial Rep to get a NIF. His friend said ‘I know someone who can help you’. She introduced me to the friend. The rest is history. I offered to pay the friend, but she wouldn’t accept, saying if you need help finding an apartment or doing anything else one you’re here, then we can discuss fees.
@isochronous Yes, if you don’t have a permanent address in Europe, it’s my understanding that you need to have a representative come with you when registering.
@dancebert Thanks for reporting back, that is indeed very useful! Was it your understanding that the financial rep could be just about anyone? What exactly is the rep asked to provide when you sign up for your NIF?
Financial rep must be either a Portuguese citizen, or a non-citizen with a residence permit. Used to be a temporary residence permit was enough. If there are any requirements beyond that, I haven’t seen it mentioned.
The rep showed one of her government issued IDs, though I don’t remember which one (they have 3!).
@dancebert @cutler so do they ever send mail to the local Portuguese rep or not?
Anyone on this forum know anyone who could help me out in this regard?
I don’t know about the Portuguese rep, but when I registered with my EEA address, they never sent me anything there at least.