Plans to set up a new pension scheme for government workers are "flawed", a union official has said.
A government report recommends the creation of a voluntary defined contribution scheme for new starters.
It follows forecasts that the Manx government's pension reserve will be exhausted by 2021-22.
There is "an ongoing cash flow requirement which has to be met in order to pay pensions", said Policy and Reform Minister Chris Thomas.
Mick Hewer of the union Prospect, which represents about 2,000 employees including civil servants, said he was "very sceptical" about the proposal.
"The set-up costs are unlikely to be justified by the low levels of take-up we would expect to see," he said.
"If a voluntary defined contribution scheme actually does see take-up levels that justify the set-up costs, then this would seriously exacerbate the legacy funding gap, so either way this proposal seems flawed."
'No silver bullet'
The aim of the new scheme is to reduce the annual £45m shortfall between the money paid in by current members, and the pension payments paid out.
A voluntary defined contribution scheme would allow employees to choose their pension contributions as opposed to minimum levels set for both worker and employer.
Current employees would be given the option of moving from the current Government Unified Scheme to the new scheme.
Mr Thomas said there was no "silver bullet" to address the government's pension liability, and he believed politicians "realise that there is no miraculous fix to resolve the legacy funding gap for public sector pensions".
"The very fact that our schemes are unfunded will mean that there will be an ongoing cash flow requirement which has to be met in order to pay pensions and associated benefits", Mr Thomas said.
If approved by Tynwald later this month, the new voluntary scheme would be set up by the end of 2020.