There are seven different scenarios to become a Tax resident in Portugal listed below. In some of the cases you can backdate to the day of your arrival to Portuguese territory.
“1 – As a general rule, an individual shall be qualified as a resident of Portugal if, during the year to which the income concern:
a) he is present in Portugal for more than 183 days, consecutive or otherwise, in any 12-month period starting or ending in the calendar year concerned;
b) he is Portugal for a shorter period, but he has, on any day during the period mentioned in the previous subparagraph, a home under circumstances which imply his intention to keep and occupy such abode as his permanent residence;
c) he is, on 31 December of any year, a crew member of a ship or aircraft operated by a resident entity;
d) he is performing public functions or commissions for the Portuguese state.
2 – For the purposes of the previous paragraph, the day of presence in the Portuguese territory shall be deemed to be any day, whole or part, involving an overnight stay.
3 – The persons meeting the requirements under subparagraphs 1(a) or 1(b) shall be deemed to be resident since the first day of their stay in the Portuguese territory unless they have been resident therein on any day of the previous year, in which case they shall be deemed to be resident in this territory since the first day of the year in which any of the requirements provided for in paragraph 1 is met.
4 – An individual shall cease to be qualified as a resident as of the last day of his stay in the Portuguese
territory, except in the cases provided for in paragraphs 14 and 16.
5 – Tax residence shall be evaluated against each taxable person of the household.
6 - Moreover, an individual shall be qualified as a resident of Portugal if he is a Portuguese national who moves his residence for tax purposes to a country, territory or region subject to a clearly more favourable tax regime included in a list approved by the Ministerial Order of the member of Government responsible for the tax area, in the year that change occurs and in the four subsequent years, unless he proves that such the change was for a valid reason, such as being seconded by his employer for performing a temporary
activity on behalf of such an employer who is resident in the Portuguese territory.
7 – Subject to the period mentioned in the previous paragraph, the resident status provided therein shall subsist only as long as such change of the tax residence of the taxable person to a country, territory or region subject to a clearly more favourable tax regime included in a list approved by the Ministerial Order of the member of Government responsible for the tax area persists, and it shall no longer apply in the yea where he shall be deemed to be resident of a country, territory or region other than those.
In the meantime, if you have any questions, feel free to reply to ask.
Ana, Co-Founder @ movingto.io