How to Open Atividade (Início de Atividade) on Portal das Finanças

• You must open atividade before invoicing more than once — a genuine one-off job (ato isolado) is treated differently.
• Two decisions up front: your CAE activity code, and Regime Simplificado vs Contabilidade Organizada.
• Segurança Social registration happens automatically when you open activity — no separate filing.
• It's free, and takes minutes online via the Portal das Finanças.

If you're going to do more than a single one-off job (an "ato isolado"), Portuguese law requires you to formally open activity (abrir atividade) with the Autoridade Tributária (AT) before you invoice anyone. It's the step that turns you into a registered self-employed worker — recibos verdes — for tax and Segurança Social purposes.

Two decisions to make first

The opening-activity form asks for two things you should decide before you start: your activity code, and your tax regime.

• CAE / código CIRS — the classification code for the work you'll actually invoice for. Look it up in SICAE (Sistema de Informação da Classificação Portuguesa de Atividades Económicas) or the AT's own FAQ on CAE/CIRS codes before you file.
• Tax regime — Regime Simplificado (tax on a fixed percentage of turnover, no accountant required, the default for most freelancers) or Contabilidade Organizada (a certified accountant handles everything, mandatory once your annual turnover passes €200,000, optional below that).

The two regimes, side by side

How to open activity

1. 1
   Choose your CAE activity code

   Pick the code that matches what you'll actually invoice for — this drives which turnover coefficient applies under Regime Simplificado.

2. 2
   Choose your tax regime

   Regime Simplificado unless your projected turnover is already over €200,000 or you specifically want organised accounting.

3. 3
   Submit the declaração de início de atividade

   Online, through the Portal das Finanças, or in person at a Serviço de Finanças (or a Loja de Cidadão that has a Finanças counter).

4. 4
   Segurança Social registration happens automatically

   When you open activity at the AT, Segurança Social is notified automatically — you don't file a second, separate registration for this step.

5. 5
   Take out work-accident insurance

   Mandatory for every self-employed worker in Portugal, even part-time or alongside employment — it covers accidents during work or your commute.

If you're a foreigner working for yourself in Portugal

The general steps above apply to everyone, but what you need before you get there depends on your nationality.

• EU, EEA, and Swiss citizens: no visa or work permit needed. You just need a NIF (tax number), then you open activity, then you register with Segurança Social to get a NISS.
• Third-country citizens: you need a visa or residence authorisation for self-employed work first — typically a D2 visa (for entrepreneurs and independent workers) or a residence permit for independent activity, based on evidence of economic activity in Portugal. Once you have that, the steps are the same: NIF, open activity, NISS.

If you still need a NIF or NISS, see our NIF guide for the full document checklist.

Before you file: the three things it asks for

The declaration itself takes minutes, but it wants three decisions you cannot change casually afterwards, so it is worth having them ready:

• Your activity code — either from the art. 151.º CIRS professional table or a CAE code. This drives your Regime Simplificado coefficient, so picking the wrong one changes what you are taxed on.
• Estimated turnover to the END of the current year — not a full twelve months. Open in October and you are estimating a quarter, which is what the €15,000 VAT threshold is measured against for that first year.
• An IBAN and BIC in your own name, to attach to the activity.

The one case where you don't file at all

If you're invoicing once — a single piece of work, not a continuing activity — that's an ato isolado, and you are exempt from filing an início de atividade declaration for VAT purposes regardless of the amount. You still declare the income on your IRS return. People routinely open activity, invoice once, and then have to close it again; if it genuinely is a one-off, you never needed to.

One subtlety worth knowing: an ato isolado's value is not counted in your estimated turnover for the year you start an activity, but it does count towards the prior-year figure when a VAT regime depends on it.

The VAT decision, and the trap for non-residents

The art. 53.º exemption is what most new freelancers want — no VAT charged, no periodic declarations. It applies only if all of these hold: you have your seat or domicile in Portugal, you do not carry out exports or related activities, and your estimated turnover to the end of the starting year is €15,000 or less.

Read the first condition carefully if you are new here. The art. 53.º regime does not apply to someone without domicile or a seat in Portugal — not even if they have a permanent establishment or a Portuguese VAT registration. Arriving mid-year and opening activity before your residency is settled can therefore land you in the normal VAT regime from day one.

Cross the €15,000 line and you move to the normal regime from 1 January of the following year, with quarterly declarations due by the 20th of the second month after each quarter.

Who withholds tax from your invoices

Clients withhold IRS at source only once your prior-year Category B income passed €15,000, or from the moment you cross it during the year — and only when the client keeps organised accounting. The rate depends on what you do: 11.5% for services outside the art. 151.º table and for atos isolados, 16.5% for intellectual or industrial property income received by its original holder, and 25% for the listed professional activities.

Below that threshold most freelancers are paid gross and settle the whole bill through the annual return and payments on account. It feels like more money at the time and is not.

What you're signed up to afterwards

• Issue every invoice or fatura-recibo through the Portal das Finanças system or the ATGO app. Doing so exempts you from separately reporting your invoices by the 5th of the following month.
• Without organised accounting, classify your invoices under Serviços – IVA > Classificação de Documentos, separating sales, business expenses and investment goods.
• On the normal VAT regime, a periodic declaration each quarter, plus a recapitulative declaration whenever you invoice businesses in other EU states.
• Quarterly Social Security declarations, and three IRS payments on account if your prior-year figures trigger them.

Changing or closing it

Both have deadlines people miss. A declaração de alterações is due within 15 days of anything on your registration changing — address, activity code, regime, bank account (art. 112.º n.º 2 CIRS). A declaração de cessação is due within 30 days of actually stopping (n.º 3).

Two things worth knowing about the regime itself. If your income drops to €200,000 or below, you are moved to Regime Simplificado automatically the following year — to stay on organised accounting you must file an alterações declaration by the end of March. And switching from one activity to another is a change, not a cessation followed by a fresh start.

Keeping your registration current

If anything changes after you open activity — most commonly your turnover crossing the €200,000 threshold — you have 15 days from the date of the change to file an update, online or in person.