Mr Quah was a partner of KPMG Malaysia since 1 October 1982 and was the Senior Partner of the firm from 1 October 2000 until 30 September 2007. Prior to taking up the position of Senior Partner, he was in charge of the Tax Practice and the Japanese Practice in KPMG Malaysia. He was also a Member of the KPMG Japanese Practice Council which is the governing body within KPMG International which looks after the Japanese Practices in the KPMG world. He was also a Member of KPMG Asia Pacific Board and a Member of KPMG International Council. He retired from KPMG Malaysia on 31 December 2007.
He had served as an Independent Non-Executive Director of Public Bank Berhad Group from 30 July 2008 to 1 October 2013 until his appointment as the Deputy Chief Executive Officer of Public Bank from 1 October 2013 until 31 December 2015. Prior to that, he was an Independent Non-Executive Director of IOI Properties Berhad, PLUS Expressways Berhad, IOI Corporation Berhad and Telekom Malaysia Berhad.