Tang took up his commerce post in July 2002 as part of a line-up of new secretaries aimed at improving the government's transparency. He was promoted from Secretary for Commerce, Industry and Technology to Finance Secretary on 4 August 2003 replacing Antony Leung. Leung resigned on 16 July 2003 due to allegations of tax evasion in regards to his new car. Tang briefly served (25 May to 21 June 2005) as acting Chief Executive after Tung Chee Hwa, the former Chief Executive who resigned citing health reasons.