Tens of thousands of public servants have been offered upfront pay rises of 3 per cent in return for industrial peace at Centrelink, Medicare and the Child Support Agency.
But the Department of Human Services is offering only 1.5 per cent in the second and third year of its proposed deal, meaning there is no net improvement on the previous offers resoundingly rejected by its workers.
The offer was announced on Wednesday as travellers were warned of "significant disruption and delay" from late September as public servants from Border Force and the Immigration Department plan their most "intense and widespread" strike actions yet.
Human Services' spokesman Hank Jongen said the new offer to the department's 34,000 staff meant they could get "more benefit to their salary".
"We are presenting staff with more benefit to their salary from the get-go, which means more pay over the duration of the agreement," the spokesman said.
"In addition, we are continuing to offer 2.75 per cent salary advancement each year for eligible staff."
A key battleground in the dispute has been the legal status of pay and conditions, with workers worried they would not be enforceable, but Mr Jongen said the new proposal was "similar" to the current agreement, which still covers DHS workers despite expiring more than two years ago.
"We have taken on board key concerns raised by staff and the new proposal is similar to the current agreement," Mr Jongen said.
"All proposed terms and conditions are covered either in the new agreement or relevant legislation, such as the Long Service Leave and Maternity Leave Acts.
"We are confident we have an attractive offer for staff to consider that is affordable while also meeting the department's operational requirements and the government's bargaining policy.
But the Community and Public Sector Union said DHS's latest offer still stripped away workplace rights and and conditions in the department.
"DHS management claim they've considered the key concerns of staff, but this revised offer clearly shows the opposite," the union's deputy national secretary said.
"This dispute has never been about money – DHS staff are rejecting what's being offered because it would strip away their essential workplace rights and conditions."
The union also announced on Wednesday that its members would embark on a week of rolling stoppages at international airports, cruise ship terminals, cargo facilities and other sites between September 26 and October 2, with "further action planned as needed".
The union has applied for protected action status for a new industrial tactic: 30-minute strikes by its members all day, every day.
The union's national secretary, Nadine Flood, warned on Wednesday morning that she expected the multiple short strikes, designed to make it difficult for departmental management to respond, to cause significant disruption and delays.
"This will be strike action on a major scale, an unprecedented escalation to make government finally do something to end this 1000-day dispute," Ms Flood said.
"Based on previous experience this strike action has the potential to cause more significant disruption and delays for international air passengers and others, but it's important to emphasise that our members don't take industrial action to inconvenience the public."
The Immigration Department did not respond to a request for comment.