The move comes as the government continues to promise to "get on with the job" of finding $50 million in budget savings after canning plans for a legislated wage freeze.

An extra 500 Tasmanian public servants are now facing the axe, among them front-line workers.

The job losses are on top of 700 full-time job cuts outlined in the August state budget.

Unions Tasmania president Roz Madsen said she was hopeful department heads would agree to negotiations, despite government ministers refusing to do so.

Ms Madsen said unions could see no other option.

"We hope the agencies will be in a position to commence the negotiations with us to deliver the government the savings it needs to address its budget concerns," Ms Madsen said.

"Then we can resolve it through the Industrial Commission."

Ms Madsen said if approaching agencies failed, there would be nowhere else to go but directly to the commission.

"We would then put wage restraint options directly to the Commissioner rather than over the bargaining table," she said.

Premier Hodgman said the unions could take whatever course of action they considered appropriate, but the government had made a decision on the job cuts and planned to deliver on its promise.

"The Treasurer and I are meeting with all agency heads over coming days," Mr Hodgman said.

"The instruction has gone out that our expectation is that these savings will be achieved and that includes the extra job reductions," he said.