Philip Gaetjens will take over as head of Treasury, and as a member of the Council of Financial Regulators, from the beginning of August. He replaces John Fraser, whose resignation the federal government announced yesterday. Gaetjens was chief of staff to former treasurer Peter Costello's from 1997 to 2007 and has held the same post during the tenure of the present treasurer, Scott Morrison.He served as secretary of the New South Wales Treasury from 2011 to 2015. He also held senior positions in the Department of the Prime Minister and Cabinet and the South Australian Treasury and Finance Department.