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.

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.