Australians are spending millions to create Peter Dutton's new Home Affairs Department, including $1.8 million for an "executive headquarters" a short drive from existing buildings, and $9,000 on new bookmarks.

Key points: New headquarters to "co-locate executive functions" in one place in the parliamentary triangle to cost $1.8m

New headquarters to "co-locate executive functions" in one place in the parliamentary triangle to cost $1.8m During Senate Estimates, department secretary described the cost as "quite modest"

During Senate Estimates, department secretary described the cost as "quite modest" Labor wants the Government to justify the expense

Labor has demanded the Government justify the expenditure as Treasurer Scott Morrison emphasises "restraint" in the lead-up to the May budget.

Shayne Neumann, Labor's spokesman for immigration and border protection, told the ABC while he would always listen to the advice of security agencies, "it's up to Peter Dutton to explain all costs associated with establishing the Department of Home Affairs — including the final cost of establishing a Home Affairs Executive Headquarters".

According to new information released as part of the Senate Estimates process, the department estimates capital costs involved in setting up the new portfolio to be $2.7 million. Other costs had reached $2.3 million at the end of January.

The largest single cost is $1.8 million to establish a new "executive headquarters" near Parliament House in the suburb of Barton.

A spokesperson for the Department of Home Affairs stated there was a "requirement" to "co-locate a number of departmental executive functions into one location in the parliamentary triangle, in close proximity to the portfolio agencies".

"The new headquarters will allow the department, from a physical security point of view, to handle information at the top-secret and above level, which is different and on a more routine basis than was needed by the former Department of Immigration and Border Protection."

The main building of the Department of Home Affairs is in the Canberra suburb of Belconnen, 15 minutes' drive from Barton.

The Department is already spending hundreds of millions of dollars to move some staff to a new building at Canberra Airport, less than 10 minutes' drive from Barton.

Costs for new department 'quite modest'

During the Estimates hearing in February, Home Affairs secretary Mike Pezzullo described the cost of setting up the new department as "quite modest".

"I'd be very surprised if it broke single digits," he said, referring to the total cost being unlikely to exceed $10 million.

The department's new website cost $70,000 and replacing building signage another $85,400.

New bookmarks with updated departmental contacts were $9,149 and new corporate templates are estimated to be approximately $5,320.

IT costs have been estimated at $800,000.

The Department of Home Affairs was established at the end of last year, as "a direct response to the increasingly complex and challenging security environment facing our country" according to a joint statement between the Prime Minister and Mr Dutton.

It brings together security, law enforcement and criminal intelligence agencies in one Government portfolio.

Intelligence and law enforcement agencies under previous arrangements disrupted 14 terrorist attacks between 2014 and 2017.

Earlier this week Treasurer Scott Morrison declared the coming budget would continue to exercise restraint.

"Australians are continuing to make sure that their belts are tightened and the Government is no different so there will be a budget that lives within its means," he said.