For auditors, license to practice is granted on the basis of reciprocity. In an audit firm, the majority of the shareholders (individuals or other auditing firms) have to be licenced in the EU.
"Article 3 - Licensing of chartered accountants and auditing firms (Article 3 of the Directive) [...]
4 . The following conditions must be met cumulatively for the granting of a professional license to an auditing company:
(a) natural persons carrying out statutory audits on behalf of the audit firm must meet the conditions laid down in Articles 5 and 7 to 11 and / or 13 and have obtained a professional license in Greece;
(b) most of the voting rights in an audit firm must be held by audit firms which have been professionally licensed in any Member State or by natural persons who meet at least the requirements of Articles 5, 7 to 11 and / or 13;
(c) the majority of the management or management body of the audit firm must belong at least 2/3 to audit firms which have been granted a professional license in any Member State or to natural persons for whom the conditions laid down in Articles 5, 7 to 11 and / or 13. Where the governing body has only two members, at least one member must meet the conditions of the present case,
(d) the audit firm meets the condition set out in Article 5.
[...]
Article 13 - Licensing of chartered accountants from other Member States (Article 14 of the Directive)
1 . Certified public accountants who have obtained a professional license in any Member State have the right to obtain a professional license in Greece, provided that they pass the special professional examinations, conducted in the Greek language within the framework defined by the case of par. .1 of article 3 of p.d. 38/2010 (AD78).
[...]
Article 50 - License to practice profession in third country auditors (Article 44 of the Directive)
1 . The E.L.T.E. by decision of the Board A professional license may be granted to a third-country auditor if, in its discretion, the conditions laid down in Articles 5 and 7 to 12 are met. The license shall be granted on the condition of reciprocity. [...]" (Law on Compulsory audit of the annual and consolidated financial statements, public oversight of the audit work and other provisions (4449/2017), last amended by Law 4706/2020, Articles 3, 13 and 50 [google translation based on unofficial text at kodiko.gr])
Law on Compulsory audit of the annual and consolidated financial statements, public oversight of the audit work and other provisions (4449/2017), last amended by Law 4706/2020, Articles 3, 13 and 50
[<a href="http://www.et.gr/idocs-nph/search/pdfViewerForm.html?args=5C7QrtC22wEsrjP0JAlxBXdtvSoClrL8kY_IXd9bfk8pCCmqt4mgGEHlbmahCJFQEmRQwePEviF8EeCoaT0MAKztT3Sb63xk3VkL3PiCQ3RLoVYQqjKiogfu8Gq1RKKQmyoZK8o4WQMyUSqXlNq21AHMLhtR8kMm7qaMD3hr-ZLJF4vXW1wSZw..">Law (official)</a>],[<a href="https://www.kodiko.gr/nomothesia/document/251518">Law (unofficial)</a>]