Contracted cleaners at the Department of Immigration and Border Protection are receiving $2 an hour less, even though Prime Minister Tony Abbott and Employment Minister Eric Abetz said this would not happen.
The annual wages of cleaners who work at the department's buildings in Canberra will this year be reduced by thousands of dollars, according to pay slips obtained by Fairfax Media.
The wage reduction has exposed the cleaners to an increasingly insecure industry in the nation's expensive capital.
Almost a year ago Mr Abbott and Senator Abetz said the scrapping of guidelines affecting some cleaners would not hurt the pay packets of workers.
"I want to make it absolutely crystal clear that no cleaner's pay is reduced," Mr Abbott said in question time last June.
During the same response Mr Abbott also said no one could be paid below the award wage, despite protests from opposition leader Bill Shorten that he had not asked about the award wage.
On the same day Mr Abetz issued a press release which said: "No cleaner will have their wages reduced as a result of the guidelines ceasing to apply."
The Commonwealth Cleaning Services Guidelines, abolished during the Abbott government's first omnibus red tape repeal day, ensured a floor price for outsourced cleaners working in government buildings and guaranteed future pay rises.
A letter sent by the department's cleaners to Immigration and Border Protection Minister Peter Dutton said the pay cut "may not seem like much to you but when you don't earn a lot this really does make a big difference".
"Due to the uncertainty around the removal of the guidelines, the tender of the contractor we work for was based on three different pay rates, " the letter said.
"Unfortunately the department chose to accept a reduced pay rate which the contractor has now passed on to us."
The cleaners asked Mr Dutton to reverse the decision and said "until very recently" they were paid enough to cover rent and other bills on time.
United Voice spokeswoman Lyndal Ryan said the government was either ignorant of the facts or it had lied and that companies were essentially forced into reducing wages without the guidelines.
"We know contracting produces a race to the bottom," Ms Ryan said.
"If this company (with the Immigration contract) didn't do this, another company would have come in and reduced wages.
"This will keep happening."
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The women cleaning Mr Abbott's office had their hopes of an 85 cent an hour pay increase thwarted when the guidelines were scrapped because the guidelines had ensured future pay increases. From the union's point of view, these cleaners could also face a situation where wages were reduced at some point in the future because of the abolition of the guidelines.
The guidelines did not apply to all of Australia's cleaning workers and Senator Abetz said last year they were a way for United Voice to boost its membership and that workplace relations laws, the modern awards system, and the Fair Work Act already provide strong safeguards for workers.
"These guidelines required that each new employee be given information about union membership by union officials," he said last year while pointing out some disparities.
"Comcare is required to apply the guidelines in its Canberra office, but not in any of its six other offices because the cleaning is provided by the building owner or the contract doesn't meet the financial thresholds of the guidelines.
"There is no need for this additional red tape which costs the suppliers $5m per year."
At Parliament on Monday Labor senator Doug Cameron said: "This is a government that can't be trusted on anything that they say.
"It's a government that does not care about how the battlers get through week to week when paying their bills and getting their kids to school."