The appointment of a former coalition ministerial staffer as head of Treasury undermines the department's reputation, says Bill Shorten.
Treasury boss John Fraser will step down on July 31 to be replaced by Philip Gaetjens, a former chief-of-staff to Liberal treasurers Peter Costello and Scott Morrison.
Mr Gaetjens was also secretary of the NSW Treasury between 2011 and 2015 and served as a senior executive in the Commonwealth Treasury, the Department of the Prime Minister and Cabinet and the South Australian Department of Treasury and Finance.
Mr Shorten told reporters on the campaign trail in the South Australian seat of Mayo on Friday it was a political decision.
"The Liberals are addicted to stacking positions in the government with their mates and this is undermining the reputation of Treasury," Mr Shorten said.
"We've seen the government use the Department of Treasury, which should be very independent, to provide politicised reports to help the government's propaganda - I think this is a worrying trend."
Mr Morrison said Mr Gaetjens brought "significant experience" to the job.
The appointment of Mr Gaetjens, an expert in micro-economic reform, has raised speculation Treasury may take on a bigger role in one of the government's major policies - the national energy guarantee - the final design of which is due to be discussed at an energy ministers' meeting on August 10.
Meanwhile, another former Liberal staffer Michael Brennan has been appointed the new chairman of the Productivity Commission for a five-year term starting in September.
Mr Morrison said Mr Brennan was unanimously chosen after a full merit-based selection process to replace Peter Harris as head of the government's key advisory body on micro-economic policy and regulation.
Mr Brennan served as deputy secretary for the Victorian Department of Treasury and Finance before joining the Commonwealth Treasury as the deputy secretary of the fiscal group.
He has been a staffer to former Finance Minister Nick Minchin and former Victorian treasurer Kim Wells.