The disclosure, which comes as a major embarrassment to the public service, was made this afternoon.
Revenue said the Houses of the Oireachtas Service was among 131 individual taxpayers, companies or bodies which had made substantial settlements – totalling €23.25m – in the first three months of the year.
The body is the office of the public service which provides administrative services to the Houses of the Oireachtas and employs 378 civil servants.
A spokeswoman said it had made a voluntary disclosure to the Revenue in 2012 relating to potential benefit in kind implications of providing taxis to staff who worked late.
This prompted a wider audit by the Revenue, which also uncovered other benefit in kind issues in relation to car and meal allowances.
The spokeswoman said the settlement was not related to any elected politicians and was purely in connection with staff tax issues.
The largest settlement published to today involved a retired medical consultant, who was hit for €2.6m in tax, interest and penalties.
Maurice Fenton, of Cunningham Road, Dalkey, Co Dublin, was investigated by the Revenue in a case involving under declared income tax and capitals gains tax.
A retired Dublin guesthouse proprietor also made a settlement of €2.2m in tax, interest and penalties.
Clare Campbell of St Mary’s Road in Ballsbridge was audited by the Revenue in a case involving under declared capital gains tax.
A Robert Campbell, with the same address, made a settlement of €555,000, also related to an under declaration of capital gains tax.
Of the 113 cases published, 48 were for amounts exceeding €100,000. Some 13 of these exceeded €500,000.
Seven of the settlements published, yielding €2.32m, related to Revenue’s investigation into offshore funds.
Shane Phelan Public Affairs Editor