To apply for a Portugal airport transit visa, you need to provide the following documents:
A filled and signed application form. If the applicant is a minor or incapacitated, the form should be signed by their legal guardian.
Proof of transport reservation, like a return ticket.
A recent passport photo.
A visa for your final destination country, if needed.
A valid travel document, with at least 3 months validity after your planned exit, along with copies of previous passports and visas.
Proof of legal status if your nationality is different from the country where you’re applying.
Documentation regarding your economic and employment situation, including a work certificate, salary details, and the last three bank statements to demonstrate financial means for your trip and return home.