There has been a sharp rise in the number of extra hours being worked by prison officers with nearly €51m in payments since the start of last year.
New figures show €9.55m was paid to prison employees through the additional hours system between April and June of this year as jails try to cope with record overcrowding.
Expenditure is up by around 5% in the first half of this year with payments in 2024 coming to almost €17.3m.
The Irish Prison Service said that the total for extra hours worked during all of 2023 had been around €33.5m.
The payments are made under the additional hours system, which was introduced around 20 years ago to replace a more costly overtime scheme.
However, the cost of the scheme has been rising as the Irish Prison Service grapples with the highest ever numbers of people in custody.
A briefing for Justice Minister Helen McEntee earlier this year said additional hours were being used to plug the gaps caused by the "slow levels of recruitment in 2023, increasing prisoner population, prisoner services, escorts etc."
One Department of Justice briefing said: "These hours have been provided to prisons which are experiencing significant staff shortfall and/or increased prisoner numbers".
"The additional hours are to support a safe system of working in the management of prison landings which are overcrowded. The scheme is dependent on volunteers being available," the briefing added.
Another submission from earlier this year said a major budget risk for the prison service was a shortfall in their pay allocation.
It said there were 200 existing staff vacancies with a risk of a "significant overspend" if all of those positions were filled in 2024.
The submission said there was also a growing demand for additional hours, legal costs, and rising bills because of the cost-of-living crisis.
A spokesman for the Irish Prison Service said: "Overcrowding in prisons requires a number of additional tasks to be completed and increased demand driven by prisoner numbers".
"This includes extra supervision in prisons on landings and access to services such as education and in-reach programmes," the spokesman said.
"Increased prisoner numbers also increase the number of prisoners requiring escort to court, hospital outpatient appointments and hospital inpatient duties," he stated.
He added that costs could fluctuate significantly across the year depending on court sessions and increased hospital attendance in winter.
Reporting by Ken Foxe
