A dozen cleaners at the Department of Foreign Affairs and Trade in Canberra do not know whether they will have a job in March.
The scrapping of the Commonwealth Cleaning Guidelines means a new contractor does not have to offer existing staff a job.
The United Voice union said the contract held by ISS was about to end and it appeared the company would not be offered the chance to renew the arrangement.
The union's ACT secretary Lyndal Ryan said it had been impossible for her to find out who the new contractor was even though the existing agreement expired in weeks.
"These contracts change every three to five years - can you imagine losing your job every three to five years?" she said.
It is not known whether DFAT's tender offer stipulated existing employees needed to be offered jobs. If it did, they were yet to be contacted by any prospective employers.
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Ms Ryan said cleaners under the current legislation encountered difficulty building a stable life because they found it hard to get a loan.
A DFAT spokesman said the contract for cleaning the RG Casey building was put out for tender under the Commonwealth Procurement Rules to ensure the best value for money for the department.
"The result of the tender process is yet to be finalised and a contract awarded to a successful respondent," the spokesman said.
"While the result is imminent it would be inappropriate to comment at this stage."
When asked about the removal of the cleaning guidelines St Vincent de Paul Society national council chief executive John Falzon said more people in paid work across Australia were asking his organisation for help.
"This policy setting adds to the growth of the working poor - it very much points in the direction of the United States," Mr Falzon said.
"It happens when you've got a poorly protected and poorly regulated labour market.
"It's troubling to be looking down the barrel of austerity measures especially when there are moves to question the importance of the minimum wage and penalty rates."
The increase failed to come through because the Commonwealth Cleaning Guidelines were scrapped during the first round of the Abbott government's war on red tape.