Federal parliamentary authorities have been urged to replace the building's Federal Police protection officers with private security guards at nearly half the price.
But with the nation's terror alert upgraded on Friday, Parliament looks likely to continue to be protected by AFP guards although the two agencies are still haggling over the terms.
Department of Parliamentary Services boss Carol Mills ordered a value-for-money review into the security arrangements at the end of Parliament in August 2013, telling politicians that "we have to get best value for our buck".
DPS also shared the view of the Defence Department that the threat of an attack on Parliament or military establishments in the capital was much reduced.
But almost a year into the next Parliament the deal with the AFP to provide the protective services operatives has still not been signed, with the arrangement carrying on by way of an "exchange of letters".
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The AFP protective services officers, specially trained in anti-terrorist first response tactics as well as close protection work, patrol the building's exterior and extensive grounds while DPS officers are responsible for internal security.
But The Canberra Times understands that private sector consultants Callida, which conducted the review, told the Department of Parliamentary Services that an AFP officer stationed around the building cost around $80 an hour while a private firm could do the job for $45 a guard.
The Canberra-based consultants were unavailable for interview on Friday.
Australian Federal Police Association chief executive Dennis Gellatly said protective services employees, who are not fully fledged AFP officers, remained the best choice for protecting the national Parliament.
Mr Gellatly said APS guards could draw on the networks, intelligence and know-how of their colleagues in the national force as well as the Canberra local police, another branch of the AFP.
"The present model of security at Parliament House is one we wholeheartedly support and not just because protective services officers are our members, but because of what the building represents, its national focus," he said.
"It comes down to the AFP being the best agency to be on the ground."
But the association expects to see a trimmed presence around the grounds of Capital Hill with the cash-strapped DPS determined to save money on the deal.
"There is the potential for a drawdown of protective services staff up there, but I'm sensing that we're unlikely to see the withdrawal of Protective Services completely," Mr Gellatly said.
A DPS spokeswoman refused to comment on the contents of Callida's report, saying the department would not discuss security arrangements publicly.
"The report is useful, of high quality and made sensible observations and recommendations," she said.
"DPS has been working with the AFP on aspects of that report."
An AFP spokeswoman confirmed that a deal had still not been finalised with the parliamentary authority.
"The AFP and Department of Parliamentary Services (DPS) are currently in negotiations to extend the MOU between the AFP and DPS for the provision of protective security at Parliament House," the police spokeswoman said.