A five-star hotel bill in Jerusalem, and an air ticket from Thailand to Dublin for a banking expert were among the costs incurred by the IBRC Commission over the past year and a half.
The inquiry, which has been operating for five years, was originally expected to cost around €4 million but the final bill is likely to be at least ten times that.
A breakdown of expenditure by the Commission details more than €2.5 million of those costs, including hotels, flights, and over €1.7 million in legal bills.
Separately, staff costs for the inquiry for the period January 2019 to June 2020 were €453,959, according to details released to Right to Know under FOI.