NIF, NISS and AIMA: getting Portugal's three numbers and dealing with the immigration agency
Before you can rent a flat, sign a phone contract or see a GP in Lisbon, you need numbers. Three of them, in roughly this order, plus a residence card from AIMA, the agency everyone has an opinion about.
The short version
- NIF (tax number): get it first, ideally before you move. It's free, and you can apply through a representative online or in person by appointment [3][4].
- NISS (social security number): apply online with the Segurança Social form, or your employer can request it [4].
- Número de utente (health service number): ask at your local health centre once you're resident, with your residence certificate, passport and NIF [1].
- AIMA (Agência para a Integração, Migrações e Asilo) handles visas and residence cards [1]. It took over from the old SEF in October 2023.
- Brits who lived in Portugal before 1 January 2021 have Withdrawal Agreement rights and a dedicated Brexit line at AIMA [5].
The NIF: your tax number
The NIF (Número de Identificação Fiscal) is a nine-digit number; for foreigners it currently starts with a 3, and it stays the same if you later register as resident [3]. The AT (the Autoridade Tributária, Portugal's HMRC) says it's essential for jobs, contracts, bank accounts and social security [3]. In practice you'll be asked for it buying a SIM card, at the chemist's and at the till in Continente, where "contribuinte?" means "do you want your NIF on the receipt?" (say yes once you're resident: some spending earns tax credits).
How to get one
| Route | How it works |
|---|---|
| Online, from the UK | A representative with a power of attorney applies through the AT's e-balcão service. Lawyers and solicitadores don't need the signature on your power of attorney certified [3] |
| In person in Portugal | At a Serviço de Finanças or a Loja do Cidadão, by appointment. Book on the AT phone line, 217 206 707, weekdays 9:00 to 19:00 [4] |
You'll need your passport and proof of your UK address if it isn't on your ID [3]. If you apply in person as a non-EU citizen, your passport should show your entry stamp or visa [3][4]. The NIF itself costs nothing [4]. Plenty of firms charge to arrange one remotely; that's a fee for their time, not the government's.
The fiscal representative question
This trips up a lot of Brits. Since Brexit, a UK resident is a non-EU resident in the AT's eyes. Getting a NIF doesn't by itself require a fiscal representative, the AT says, but once you have a "tax relationship" with Portugal (a lease or property, a job, self-employment, a car), you have 15 days to either appoint a representative or sign up for electronic notifications through the Portal das Finanças or the ViaCTT electronic mailbox [3]. Fail to do either and the fine runs from EUR 75 to EUR 7,500 (about £62 to £6,250) [3]. Self-employed people need a VAT representative regardless [3].
Once you move and become resident, update your address to Portugal with the AT. The representative requirement falls away, and you'll want access to the Portal das Finanças for your tax return; see Portuguese taxes for Brits.
Pound conversions use the Bank of England spot rate of 5 November 2026 (£1 = EUR 1.2002).
The NISS: social security
The NISS (Número de Identificação da Segurança Social) is your social security number, the rough equivalent of a National Insurance number. You need one to work, to be self-employed and to claim benefits [1][4].
- Apply online using the Segurança Social online form for foreign citizens, or let your employer request it when you start a job [4].
- Send the documents. For Brits (third-country nationals) that's a passport plus a visa or residence authorisation, something showing your work situation (an employment contract, proof you've registered as self-employed, a digital nomad contract or voluntary social insurance), and proof you've applied for residence if you're still waiting [4].
- Collect it. You'll get a registered letter and pick up the NISS at a Segurança Social office. Book through the SIGA platform or app, or by phone on 210 548 888 or 300 088 888, weekdays 9:00 to 18:00 [4].
- Check progress on Segurança Social Direta, the online portal [4].
It's free [4]. The government's guide also says foreigners with an address in Portugal can ask for the NIF, the NISS and the health service number together in one application [4], which saves a fair bit of faff.
If you're posted by a UK employer, you may stay in UK National Insurance instead; see working abroad for a UK employer.
The utente number: the health service
To use the SNS (Serviço Nacional de Saúde), you register at your local centro de saúde (health centre) and ask for a Número Nacional de Utente [1]. Bring your residence certificate, passport and NIF [1]. Once registered, the FCDO says, you have the same rights to treatment as a Portuguese citizen [1]. UK State Pensioners should register their S1 with Segurança Social first. Our guide to the SNS and your utente number covers the rest.
AIMA: the immigration agency
AIMA took over visas and residence from SEF (the old Foreigners and Borders Service). You come in on a residence visa issued in the UK, then apply for a residence card after you arrive [1]. A temporary card needs renewing every two to three years, and after five years you may qualify for permanent residence [1]. It's a legal requirement in Portugal to carry a valid residence document [1].
The honest truth is that AIMA has had serious backlogs, and appointments can be hard to get. A few things help:
- Use the right channel. AIMA's contact centre is on +351 217 115 000, weekdays 8:00 to 20:00 [5]. It has added online contact forms for some requests, including one for permanent residence in November 2026 [5].
- Report changes. Tell AIMA if your address, email or name changes; a new card may need an appointment [1].
- Lost card? Report it to the police first and get a copy of the report before asking AIMA for a replacement [1].
- Keep everything. Appointment confirmations, payment receipts and emails are your proof of a pending application if anyone asks.
Rules on the validity of expired documents while renewals are pending have changed several times since 2020. Check AIMA's site or the FCDO's Living in Portugal guide before you travel on an expired card.
Withdrawal Agreement residents
If you lived in Portugal before 1 January 2021, you're covered by the Withdrawal Agreement and should hold a residence card under it [1]. After five years you can apply for a permanent card valid for ten years [1], and AIMA has a contact form for moving from temporary to permanent rights [5].
No card yet? Email brexit@aima.gov.pt with evidence you were legally resident before 2021, or that you'd moved permanently by then if you never registered [1]. If AIMA asks for more documents, reply within 10 working days [1]. At your biometrics appointment, bring your passport, proof of address, any old EU residence document, NIF, utente number and NISS if you have one; if you're still waiting for a number, go anyway [1]. AIMA's Brexit line is +351 214 236 709, working days 8:00 to 14:00 [5].
Your card matters at the border too. Long-term residents of a Schengen country are exempt from the EU's Entry/Exit System, so carry your card and passport together when you travel, because border staff need to see your status; visitors without residence are limited to 90 days in any 180 [2]. See Brits in the EU after Brexit.
Your first fortnight in Lisbon, in order
- NIF before you arrive, or on day one at a Finanças office.
- Bank account with your NIF; see banking in Portugal.
- Lease on a flat, which gives you an address for everything else.
- AIMA appointment for your residence card, if your visa route requires it.
- Atestado de residência (residence certificate) from your junta de freguesia, the parish council, which the health centre will want.
- NISS if you're working, and the utente number at your health centre.
It's a slog, but it's a one-off. Members of our community group for Brits in Portugal swap tips on which Lisbon offices have shorter queues, and that alone can save you a morning.
Sources
- GOV.UK (FCDO): Living in Portugal (last updated 10 July 2026)
- GOV.UK (FCDO): Portugal travel advice, entry requirements (updated 11 August 2026)
- Autoridade Tributária: NIF for foreign non-resident citizens (July 2025)
- gov.pt: Como pedir o NIF e o NISS para pessoas estrangeiras em Portugal (updated 2 September 2026)
- AIMA: Brexit and AIMA home page (checked 8 November 2026)