Taxpayers have been left with a bill of nearly $100 million in the past year as the cost of public service workers' compensation claims continues to climb.

Federal government workplace insurer Comcare will unveil a $98 million loss in its annual report, blaming more psychological claims in public service workplaces and "injured" bureaucrats staying off work longer.

The scheme's long-term liability for payouts is now more than $2.6 billion, with more than 30 per cent of it unfunded, and last year's horror losses of more than half a billion dollars have been revised upward to a book loss of $670 million after changes to accounting practices.

Federal departments and agencies had to find an extra $70 million for workers compensation premiums in 2012-2013 and are looking at another 18 per cent increase in 2013-2014 as Comcare tries to fund its long-term liabilities.

Despite Comcare's win in the High Court on Wednesday against a public servant claiming compensation for injuries sustained while having sex, the results look set to intensify the momentum for reform to public sector workers' compensation.

Despite accepting fewer claims in 2012-2013 than the previous year, the cost of payouts, including medical, legal and other overheads, grew by nearly $40 million to $360 million in 2012-2013.

Comcare chief executive Paul O'Connor, in his foreword to the report, said the stay-away rate and growing numbers of public sector psyche claims were to blame for the scheme's continued financial woes.

"Psychological injury costs continue to rise and the length of time ill or injured people are away from their work has worsened at public sector workplaces," Mr O'Connor wrote.

In March a review of the scheme ordered by previous Labor Government ordered a review urged sweeping reform to cut down on dubious claims for psychological injuries, payouts for dodgy therapies, doctor shopping and outright fraud.

The review made more than 147 recommendations to rewrite the legislation on federal public sector compensation claims with the aim of getting injured bureaucrats back to work and ending their "passive" reliance on compensation.

But legislation to implement changes has stalled with the change of government.