Renting a house or apartment in Portugal can be complicated for non-Portuguese as most landlords not only request a deposit and at least one month’s rent in advance but a fiador as well. (This normally isn’t required when you rent a room.)
A fiador is a guarantor, or someone who’ll pay the bills if you’re unable to pay them. It can’t just be anyone, however. First of all, the fiador has to be a Portuguese resident, which is often a problem for most newcomers to Portugal as most people don’t have family or friends in Portugal that they can ask to be their guarantor.
Portuguese landlords normally want someone who is resident in Portugal as the fiador, although it can be worth asking if the landlord will accept someone who lives abroad as the fiador. And, if you do find a Portuguese person or someone resident in Portugal to be your fiador, it can’t just be anyone either. That person needs to prove that they have the means of being your gaurantor (usually by showing their tax returns or payment slips).
Most people ask a family member, such as a parent, but as someone who’s just moved to Portugal your only option may be asking a friend or colleague that lives here. This is a big ask, as they’re taking on a lot of legal and financial responsibility, and with no expiry date, so keep that in mind.
Alternatively, a bank can be your fiador for a fee through a service that’s called Garantia Bancária or some landlords will allow you to pay several months upfront instead (usually 6-12 months). A lot will depend on how popular the property is: if the landlord can find another tenant with a fiador, they may opt for that instead.
Another way around the fiador issue is to use a website like Flatio to book your apartment (these are mainly available in cities like Lisbon and Porto). While you do pay an Airbnb-style booking fee to book an apartment through these sites, a fiador isn’t normally required.