The majority of public servants will not be affected by the increase in the state pension age, it has emerged.
As the backlash grows over the age rise, it has been confirmed that many public service employees can retire early and receive a supplemental payment until the state pension kicks in.
In contrast, private sector workers who are legally obliged to retire at 65 cannot claim the state pension until they are 66.
The state (PRSI) pension age is due to rise to 67 next year, prompting a scramble by politicians to promise to row back on the plans as the issue comes up on the doorsteps during general election canvassing.
Thousands of workers who are compelled to leave work aged 65 have to claim Jobseekers' Benefit and receive €45 a week less than they would from their pension.
However, many public servants sidestep this change in the rules.
This is because large numbers of them qualify for a "supplementary pension" before they can qualify for the state contributory pension at 66.
The supplementary pension can be claimed years earlier.
The Department of Public Expenditure confirmed that the supplementary pension exists.
Pension experts said it means public servants have insulated themselves from the rise in the state pension age.
The latest version of the protection for public sector workers came when then minister for public expenditure Brendan Howlin signed a statutory instrument in 2014 when the new, higher state pension age was introduced.
The supplementary pension deal was struck with the public service unions as part of the deal to integrate their pensions with the state pension.
It applies to public servants who joined after April 1995.
Pensions expert Tony Gilhawley, of Technical Guidance, said: "Public servants who joined after April 6, 1995 - the majority of the current public service workforce - and who are en- titled to the state pension can be paid a 'supplementary pension' by the State if they retire before the state pension age to make up for not getting the state pension until later."
He said it was unfair that a public service employee who retires at, say, 63 can get a top up or supplementary pension from the state equal to the state pension between 63 and 67 if they do not work.
"It's a case of inequitable treatment. One sector of the workforce gets insulated from the increase in the state pension age at the taxpayer's expense, but the other - the private sector - doesn't," Mr Gilhawley said.
Asked why public servants had protected themselves from the state pension changes, a spokesperson for the Department of Public Expenditure and Reform made no comment.