Your future son-in-law, as a third-country national, is prohibited from engaging in paid activity while in Portugal under a short-stay visa (Schengen visa), in accordance with Article 11 of Law no. 23/2007. Furthermore, under Article 59, Portuguese law generally does not permit a change of visa type from within the national territory, except under exceptional circumstances defined by law. Therefore, he must return to his country of origin or legal residence to apply for any long-term residence visa (e.g., for employment, family reunification, or job search). Remaining in Portugal beyond the validity of the Schengen visa, or performing unauthorized work, constitutes an administrative offense under Article 183, and may lead to penalties including removal measures and entry bansunder Article 134. Before exiting the country, he should collect the necessary supporting documents, such as a valid passport, proof of financial means, accommodation, criminal background certificate, and health insurance. Once approved through the Portuguese consulate, he may enter Portugal legally and request a residence permit under Article 77, registering with AIMA (formerly SEF). Sponsoring a future son-in-law does not fall under Article 98 (Family Reunification) unless the marriage is legally established and the sponsor (i.e., your daughter) holds a valid residence permit or Portuguese citizenship. Portuguese immigration law does not recognize in-laws as eligible family members for reunification unless the marriage is formalized. However, the future father-in-law may assist by issuing support declarations, invitation letters, or accommodation proofs, which can strengthen the visa application but do not replace the legal requirements. The most viable path is to apply for a residence visa for subordinate employment (Article 88) or for independent professional activity (Article 89). For Article 88, a signed employment contract with a Portuguese employer is required. For Article 89, a viable business plan and registration with the tax authorities are necessary. If a legal marriage takes place, the son-in-law may subsequently apply for family reunification under Article 99, which is subject to individual assessment and approval by AIMA.
