Find your CAE activity code

CAE stands for Classificação Portuguesa de Atividades Económicas — the official classification of what you actually invoice for. You pick one when you open atividade, and it stays attached to your activity at the Autoridade Tributária.

Because it drives your Regime Simplificado coefficient — the 0.15 to 0.95 share of turnover you're actually taxed on. Two codes that sound equally plausible for the same work can put very different amounts of your revenue in front of the tax scale, so this is a decision worth getting right before you file, not after.

The opening-activity form accepts either. The art. 151.º CIRS table lists named professions and is the usual fit for classic freelance work; a CAE code classifies economic activity more broadly and suits trades and businesses that don't map onto a listed profession. If both could describe your work, the one matching what you'll invoice for is the right one.

No. This matches your description against the CAE catalogue and ranks the closest fits — it's a starting point, not a ruling. Confirm the code in SICAE (Sistema de Informação da Classificação Portuguesa de Atividades Económicas) or the AT's own CAE/CIRS guidance before you put it on a form.

Yes — you file a declaração de alterações at the Portal das Finanças. Changes to your activity details must be reported within 15 days, and it's free. It's still easier to start with the right code than to correct one after you've been invoicing under it.