The payments, detailed after additional senate estimates in February, come as senior management prepare to cut another 200 roles from a workforce of 2324 staff in 2016-17.

They reveal the majority of redundancies were sourced from the department's Indigenous affairs division, primarily from the regional network program.

The department shed a total of 79 staff in 2015 with public servants taking home an average severance payment of $57,718.

More than 350 PM&C staff have accepted voluntary redundancies since 2014 with the vast majority aged between 50 and 59 .

Slightly more than one quarter of departing staff were aged between 40 and 49 with another 50 staff older than 60.

More than 180 positions – or half of all voluntary redundancies – were based in Canberra with another 58 positions stripped from the Northern Territory.

Only 30 staff who accepted voluntary redundancies were younger than 30 with 80 staff aged between 30 and 39.

The figures were detailed in the same week two-thirds of the department rejected a revised pay deal described as "harsh and unfair" by the public service union.

According to union representatives, 74 per cent of staff cast votes in the ballot with 68 per cent rejecting the pay offer of 5.5 per cent over three years.

Staff rejected a similar offer in October with many believing the revised offer was only a marginal improvement. The offer did match the six per cent over three years offered by other departments, including defence.

A total of $3.3 million in severance pay was allocated to staff within the Indigenous affairs division during 2015, which includes those working com economic development, schools and housing policy.

In November, the department's deputy secretary of governance Elizabeth Kelly told staff the workforce was above its affordable staffing level and cuts were imminent.

"In preparation for the 2016-17 financial year, we will need to take steps to reduce our staffing levels," she said.

"This reduction can be managed through a combination of natural attrition, disciplined recruitment decisions and a voluntary redundancies round."

A department spokesman told Fairfax Media the department committed to hiring new staff amid the redundancies in an effort to bolster specialist capabilities.

"This [the reduction in staff numbers] doesn't mean that recruitment will be stopped entirely," the spokesperson said.

"[The] department remains committed to bringing in new people with fresh ideas and perspectives but as always, will do so in consideration of our broader budget and staffing levels."

The department has capped its spend on redundancy payment at $6 million for the 2016 redundancy round, although it has not detailed which divisions will be most affected.

Priority will be given to staff who are able to leave the department within months with all expressions of interest to close on March 30.