The rising costs and concern that public servants may be rorting the system have prompted departments to implement new measures to prevent injury and assist staff in their transition back to work.

Department of Employment secretary Renee Leon said public servants were taking more time off work each year, causing the costs of claims to increase.

"That is partly a function of there being a significant increase in psychological injury claims and possibly that agencies could be more proactive in supporting their injured employees to get back to work," she said.

Earlier this year, the Public Service Commission told an inquiry into reform of the Comcare system that the government could no longer afford the cost or reputational damage wrought by abuse of Comcare.

According to a Comcare report, workers' compensation claims for mental stress cost $342,000 on average, although nearly 500 mental-stress claims over the past five years cost more than $500,000.

Department of Education deputy secretary Sandra Parker said a cross-departmental group had developed a number of trial programs to address the problem, which will be assessed by the Public Service Commissioner.

"The main focus is on preventing workplace injury but also getting people back to work quickly," she said during a senate estimates hearing.

Ms Parker said a number of internal surveys had identified "hot spots" within departments where employees were unhappy and exposed to safety problems or issues.

"Often they go together with people having potentially psychological injuries or maybe bullying and harassment claims, lots of absences, which often can lead to claims," she said.

Ms Parker said each deputy secretary on the group had conducted their own staff surveys and discussions had been held with the Comcare board.

"Each agency is doing it separately, obviously, because they have responsibility for their own workers, and we need to have privacy covered."

The annual bill to taxpayers for bullying, harassment and "occupational violence" in the public service is now approaching $80 million.

Nearly 39 per cent of claimants in 2013-14 said bullying or harassment by their colleagues had left them unable to work, the same proportion of public servants who cited workplace stress as the cause of their psychological problems.

Ms Parker said the trial measures would assess whether managers were effectively mitigating risks and supporting staff.

"Do we have specific issues that higher management needs to look into and address and assist that manager with or even move a manager? Are there problems in that workplace?" she told the hearing.

The trials began in mid-2016 and the findings of an evaluation by the Public Service Commissioner will be released in coming weeks.