Mr Tham is a board member of listed companies DBS Group Holdings and Keppel Corporation and serves on the boards of Nanyang Polytechnic and not-for-profit organisations Singapore International Arbitration Centre, Tax Academy of Singapore, VIVA Foundation and Mount Alvernia Hospital. He is a past board member of the Accounting & Corporate Regulatory Authority and the Housing & Development Board and a past member of the Future Economy Council.

He is a chartered accountant by profession and was for many years in public practice at KPMG, where he was its managing partner in Singapore and then its Asia Pacific chairman and a member of its global board and exco when he retired.

Mr Tham majored in economics at the University of Leeds UK and is a Fellow of the Institute of Singapore Chartered Accountants, the Institute of Chartered Accountants in England and Wales and the Singapore Institute of Directors.