Charalampos Billinis completed his studies at the Athens University of Economics and Business (AUEB) in May 1983. Following the completion of his military service (July 1983 – September 1985), he began his professional career in October 1985 at an international audit firm, serving as a member of audit teams responsible for the statutory audit of major Greek companies that were subsidiaries of multinational groups. In 1996, he became a member of the Institute of Certified Public Accountants of Greece. In 2006, he co-founded HBP Certified Public Accountants S.A., together with Vasiliki Paschalidou, and served as Chairman and Chief Executive Officer. On 31 December 2026, HBP merged with CPA Kudos S.A., contributing to the formation of a stronger unified audit organization. He currently remains as second principal shareholder of CPA Kudos Greece, without executive responsibilities, actively contributing his extensive experience to the development and mentoring of younger professionals, particularly in the areas of acquisition due diligence, corporate transformations, specialized tax audits for individuals and legal entities, and the structuring and reorganization of corporate groups.