The APS Statistical Bulletin for December 2017 was released on Thursday, showing the number of Australian public service employees had dropped by 1.8 per cent to 150,489 in the 12 months to December 31.

According to the bulletin, this is the lowest number in the past decade, down from a peak of 166,582 people in 2011. There were 2767 fewer employees in December 2017 than December 2016, with most of the decrease attributed to a 14 per cent drop in non-ongoing employees. While the number of staff members employed for a specific term or a specific task remained steady over the 12 months, there was a drop in casual staff, from 9217 to 6967 staff employed casually.

The bulletin also tracked the creation of the new super department of Home Affairs, confirming that it is the fourth largest agency, with 14,355 staff. The Department of Human Services remains the largest department, followed by the Tax Office and Defence.

The bulletin also tracks staff changes through machinery of government changes, with 403 staff moved from the Attorney General's Department to Home Affairs. Infrastructure and Regional Development also lost a high number of staff to Home Affairs, with 267 positions moving to the new super department. Twenty-nine staff moved from Prime Minister and Cabinet, and 18 moved from Social Services to Home Affairs.

There has also been an increase in the number of women in senior roles within the public service, with women taking up 44 per cent of SES roles and 45 per cent of EL2 roles.