Prime Minister Scott Morrison will cut four entire Federal Government departments, merging their operations with others into new "super departments", and sack the bureaucrats currently in charge.

Morrison said, "Having fewer departments will allow us to bust bureaucratic congestion, improve decision making and ultimately deliver better services for the Australian people."

But the Community and Public Sector Union (CPSU) says that experience shows that isn't necessarily going to be true.

"The experiences in the (Australian Public Service), where there has been the creation of a super department with the Department of Home Affairs, has been negative, in terms of people's staff experience and the service delivery in that agency has been affected," CPSU national secretary Melissa Donnelly said in an interview with the ABC.  

"It is clear that the Prime Minister is out of ideas, first he borrowed Services Australia from the NSW Government, now super-departments. Moving buildings and merging departments does not fix the service crisis created by his own government," Ms. Donnelly said separately.  "This change will not do anything to address the 48 million unanswered calls to DHS in 2017/2018 or the further 5.3 million calls abandoned out of frustration.  These are not the actions of a good government.  This won't change the delays in the Family Court, and it won’t change the challenges our CSIRO face."