If you want to start working, and you are not a citizen of the EU and Andorra, Iceland, Liechtenstein, Norway and Switzerland, you will need to apply for a visa, which must be made with the Portuguese Embassy or Consulate in the area of residence.
To obtain your visa, the following documents may be requested:
Passport or other travel document that has a validity of at least 3 months longer than the visa;
International health insurance;
Proof of accommodation;
Proof of admission to a higher education institution / employment contract / invitation;
Proof of means of subsistence.
There are visas with several specificities, so we highlight two types:
Or Employment contract, or equivalent, of a research center or higher education institution;
Or proof of acceptance at a research center or higher education institution and having an advanced training grant or research grant;
Or a term of responsibility signed by the research center or higher education institution that guarantees admission, also ensuring accommodation costs.
Visa for Highly qualified or cultural education, additional documentation is required, namely:
Employment contract or pre-contract or service provision contract;
Invitation letter issued by an educational or vocational training institution;
Term of responsibility of a certified company, as defined by a ministerial order of the members of the Government responsible for internal affairs and the economy;
Invitation letter issued by a company or entity that develops cultural activity in national territory, recognized by the Government member responsible for culture, as an activity of interest to the country or as defined by law;
Invitation letter issued by a research center.
Note also that citizens of other countries who stay in Portugal for periods longer than 90 days must, upon arrival, apply for a Residence Permit in the Immigration and Borders Service (SEF).
On the SEF website you can find information complementary to the one mentioned here.