The mass exodus comes at a time when the Government has been criticised because of the rise in gangland and serious crime.
Gardaí can retire early if they have completed 30 years of service by the age of 50. The compulsory retirement age for senior officers is 60.
“The number of chiefs and superintendents going early is unprecedented,” said a senior Garda source.
“In the past they went incrementally and when the time came senior management would have had people, experienced people, lined up to fill the positions.
“Guards are thinking it’s better to get out before the gratuity tax comes in and not to pay the pension levy for any longer than they need to.”
National specialist units – many of them tasked with combating organised crime – are being particularly badly hit.
Key Dublin regions battling gang violence are also suffering disproportionately. Crime figures, released last week, showed alarming hikes in murders, shootings and bank robberies.
Two weeks ago, the Garda Bureau of Fraud Investigation (GBFI) lost its second in command, Detective Superintendent Eugene Gallagher. A very experienced officer, he had eight years to go.
The former head of that unit, Chief Supt Pat Brehony, left a number of months ago. He has been replaced.
Det Supt John McDermott, second in command at the Criminal Assets Bureau, is due to retire soon. He has about four years left. Other recent early retirements include Det Supt Liam Coen of the Garda Technical Bureau, Det Inspector Brendan Burke from the National Bureau of Criminal Investigation (eight years left) and three detective inspectors from the Special Detective Unit.
Det Supt PJ Durkan, based in Galway, is due to retire early in the coming months.
These retirements follow a raft of senior gardaí who were known to have retired early in recent months.
They included Chief Supt Tim Maher of Crime and Security, Chief Supt Dave Roche, in charge of Dublin Metropolitan Region (DMR) East and Supt Liam Hogan of Donnybrook Garda Station. They have been replaced.
In addition, Dublin has lost three of its six senior detectives through early retirement: Det Supt Hubert Collins (DMR West), Det Supt PJ Browne (DMR South Central) and most recently Det Supt Denis Donegan (DMR South). The first two positions have been replaced.
“These are all very experienced crime investigators,” said the Garda source. “All the recent legislation is all well and good, but you need experienced gardaí to carry out these investigations and sustain prosecutions.”
DMR West has also been hit with the early retirement of three inspectors from Blanchardstown.
Assistant Commissioner (AC) in Crime and Security Mick McCarthy retired on age grounds a number of months ago. He was replaced.
AC Al McHugh, in charge of the entire DMR, is due to leave in September on age grounds. Other recent retirements include Supt Denis Bowe, Tullamore, Supt Willie Gallagher, Roscommon and Supt Tom Commins, Boyle.
A number of other chiefs and superintendents have also indicated they intend to leave early this year.
Justice Minister Dermot Ahern has said there was a backlog of retirements due to a three-year extension of the retirement age in 2006. Mr Ahern got an exception to the moratorium on promotions last June, when the cabinet approved the promotion of 13 officers – three to chief superintendent and 10 to superintendent.