Does Portugal count days or nights for tax residency?

Most countries in this guide count any part of a day against a calendar year. Portugal does neither, and both differences change the arithmetic.

Nights, not days. Because a counted day requires an overnight stay, a same-day visit does not count, and a trip of three nights is three days rather than the four an "any part of a day" rule would produce. That makes Portugal one of the few places where counting nights — the instinct most travellers have — is actually correct.

A rolling window. The 183 days are measured across any 12-month period, so there is no 1 January reset. A pattern that looks compliant against the calendar can breach a window that straddles two years — the same structural trap as the Schengen rule, applied to tax.

Below the day threshold, Portugal also treats you as resident if on any day of the period you have a dwelling in Portugal in conditions suggesting an intention to hold and occupy it as your habitual residence.

This is not about ownership. It is about the circumstances: a place kept available and furnished for your habitual use points one way; a property let out to tenants points another. Someone spending well under 183 nights but keeping a home in Portugal can be resident on this ground alone.

• Portal das Finanças — Código do IRS, artigo 16.º (Residência)
• Agência Tributária e Aduaneira — Residência fiscal