Certified accountants must hold at least 51% of the share capital and respective voting rights of accounting firms. Non-EU nationals can only register with the Order of Certified Accountants subject to reciprocity.
"Article 9 - Professional title and practice of the profession
1 - Professionals registered with the Order are designated as certified accountants, under the terms of these Statutes, being assigned, exclusively, the use of that professional title, as well as the exercise of the respective profession.
2 - They are also certified accountants, after registration with the Order and for the purposes set out in the previous number:
a) Professionals who are nationals of Member States of the European Union and the European Economic Area, who obtain recognition of their respective professional qualifications, pursuant to Law No. 9/2009, of March 4, amended by Laws no. 41/2012, of August 28, and 25/2014, of May 2, pursuant to these Bylaws;
b) Professionals who have obtained the qualifications outside Portugal, under reciprocal conditions, provided that they obtain the same qualifications as necessary and meet the other requirements for registration, under the terms provided for in this Statute and in other legislation in force.
[...]
Article 16 - registration conditions
1 - The general conditions for registration as a certified accountant are: [...]
4 - Non-European Union citizens who are domiciled in Portugal and who meet the other conditions required in paragraph 1 are allowed to register, provided that there is reciprocal treatment by their country of origin, and the requirements may be required of the next issue.
[...]
Article 116 - Legal nature and types
1 - Professional companies of certified accountants are civil companies, endowed with legal personality, and may adopt the legal types provided for in the Commercial Companies Code or others legally provided for.
2 - The share capital and respective voting rights of professional companies of certified accountants are held in at least 51% by certified accountants, and the management or administrative bodies of said companies must be integrated in at least 51% of certified accountants.[...]" (Decree-Law No. 452/99 (1999-11-05), as amended by Law No. 139/2015 (2015-09-07), Articles 9, 16 and 116 [google translation])
Decree-Law No. 452/99 (1999-11-05), as amended by Law No. 139/2015 (2015-09-07), Articles 9, 16 and 116
[<a href="https://dre.pt/dre/legislacao-consolidada/decreto-lei/1999-185970002">Decree-Law</a>]