Taxi fares for prison inmates are set to cost the taxpayer €750,000 by the end of this year.
The prison service has spent more than €500,000 already this year on taxis, but insists it's more economic than using prison vans.
The taxis are used to ferry prisoners to court appearances, to hospitals and even for trips between prisons.
On one instance €500 was paid to bring a prisoner from Cork to Dublin.
It has cost almost €400,000 to bring prisoners to court appearances since January, with taxi drivers happy to keep their meters running for up to four hours while they wait for the return trip.
But while discussions continue with prison officers' unions on a pay deal for overtime, the prison service still insist that it is cheaper and more reliable to use taxis.