The departing Treasury secretary says his department needs to reduce its staff by one in three workers to meet budget cuts.
In a speech in Canberra, Martin Parkinson told industry professionals the Treasury Department is continuing to shrink its staff numbers from a 2011 peak of over 1,000.
Dr Parkinson, who is due to leave Treasury after this year's budget, says his department has already managed to shed its workforce by about 15 per cent, roughly half of its reduction target.
"Clearly, since we don't control the responsibilities given to us by government, change of this magnitude means delivering similar outcomes in a very different manner," he said.
"In the past, our response to increased demands was to increase our efforts: by working harder and longer.
"Needless to say, this is not sustainable, and it also crowds out any attempts to think differently â and smarter â about prioritising our resources."