The majority of the members of the governing bodies of audit firms must be licensed auditors or auditing entities of Member States. Foreigners can only register with the Order of Statutory Auditors subject to reciprocity or fulfilling certain conditions, including providing proof of residence in Portugal for at least three years.
"Article 118 - Requirements of Statutory Auditors
1 - Only entities that meet the following requirements may be registered as statutory auditors:
a) The majority of the share capital and voting rights must always belong to statutory auditors, statutory auditors, auditors or auditing entities of Member States, the rest may be held by any natural or legal person;
b) The majority of the members of the governing bodies must be statutory auditors, statutory auditors, auditors or auditing entities of Member States;
c) The firm of statutory auditors must comply with the requirement of suitability established for statutory auditors.
[...]
Article 149 - foreign registration
1 - Without prejudice to the provisions of title vi, the registration of foreigners is admitted whenever the following conditions are cumulatively met:
a) Are registered and have full rights to exercise the profession in an organization of the respective country, recognized by the International Federation of Accountants (IFAC);
b) Provide proof of residence in Portugal for at least three years;
c) Pass the law and taxation modules, as defined in the examination test for access to statutory auditor.
2 - The registration of members registered with similar bodies in the respective States may also be admitted, provided that Portuguese statutory auditors are admitted to practice their profession on equal terms with their nationals, in accordance with what is legally established. [...]" (Law No. 140/2015 (2015-09-07), in force from 2016-01-01, Articles 118 and 149 [google translation])
Law No. 140/2015 (2015-09-07), in force from 2016-01-01, Articles 118 and 149
[<a href="https://dre.pt/dre/legislacao-consolidada/lei/2015-177026851">Law</a>]