The Department of Immigration and Border Protection is looking to cut hundreds of jobs.

The department has been hit by a $116 million budget cut and a reduction in its staffing cap, and so voluntary redundancies will be offered soon.

Community and Public Sector Union (CPSU) deputy national president Rupert Evans says up to 800 of the department's 13,750 jobs could go.

“The department has announced that they are required to reduce their staffing by an average of 300 for the financial year, but in terms of how budgets and finances in public service departments work that could climb to around 800 or more,” he told reporters.

“This Government trumpets its commitment to border security at every available opportunity, yet at the same time they're slashing and undermining the department.”

A department spokesperson says voluntary redundancies will be offered to executive-level staff in the coming months.

“The department expects to offer a limited number of voluntary redundancies to executive-level employees. The final number of offers will be determined through further budget and workforce planning,” the department said.

“The move is a result of a reduction in the department's budget for 2016-17 by 4.5 per cent, or $116 million, and a subsequent year-on-year reduction in the department's average staffing level cap.

“The department anticipates making voluntary redundancy offers from late October 2016.”

The CPSU says that any changes could be made without forced redundancies.

“That is the department's position that they do not anticipate having to go to forced redundancies, but that still remains to be seen and obviously that's a pretty significant worry for workers in the department,” he said.

The union says the cuts came in the middle of rapidly-expanding workloads for staff.

“It would be bad enough if it was the same amount of work being done by less people,” he said.

“But what we're seeing is a steady increase in the amount of work the department is required to do year-on-year.

“These budget cuts are just ignoring the reality of an increase in workload.”

ACT Chief Minister Andrew Barr is outraged too.

“Despite his predecessor's firm personal commitment that the cuts would stop, today the Prime Minister proved that when it comes to sacking Canberrans, Liberals can't help themselves,” Barr said.

“After cutting thousands of jobs and putting huge strain on the Canberra businesses that rely on them, the Commonwealth now plans to sneak the Murray Darling Basin Authority out of Canberra in the dead of night to shore up a regional seat, while cutting hundreds of jobs at the Department of Immigration and Border Protection.”