The Government is unable to say how much revenue the Exchequer is losing through tax exemptions available for investors in hotels, multi-storey car parks and private hospitals.
Information disclosed by the Minister for Finance, Mr McCreevy, shows that records for a number of tax relief schemes are compiled in such a way that the Revenue cannot determine their individual cost to the Exchequer.
This was despite the availability of some of the reliefs since 1997.
Mr McCreevy said the Revenue is now working on changes to annual income return forms for the 2004 tax year which will yield "additional information" on the cost of the reliefs.
The availability of tax reliefs has been a major factor behind the rapid growth of the hotel business in particular.
Similar reliefs are available to developers of sports injuries clinics, holiday camps and holiday cottages. However, the schemes have sometimes proved controversial.
Last year it emerged that Mr McCreevy had given tax breaks to a planned private hospital after being lobbied by one of the promoters who was based in his constituency. The move was condemned by the Opposition but Mr McCreevy said it was consistent with Government policy.
In addition, the management at Beaumont Hospital, Dublin, was sharply criticised at the Public Accounts Committee last year after it emerged that the car-park scheme for which tax relief was given had resulted in losses to the Exchequer of up to €13 million.
The Comptroller & Auditor General, Mr John Purcell, told the committee in May that he had "no doubt" that a similar car-park scheme at Tallaght Hospital resulted in a loss to the Exchequer.
Mr McCreevy said in a response to parliamentary questions from the Sinn Féin TD Mr Caoimhghín Ó Caoláin, that specific information on the cost to the Exchequer of the reliefs was not readily available.
The information "could not be obtained without conducting a protracted investigation of the Revenue Commissioners' records", he said.
"Claims for these reliefs are aggregated in tax returns with other claims, such as with industrial buildings allowances generally or with other capital allowances, and do not distinguish between the reliefs claimed in respect of the different schemes."
Mr Ó Caoláin said the situation was outrageous, claiming that property-based allowances were being "gifted to privileged sectors of society" without the cost being known.
"We have no estimate of the cost of these reliefs and no analysis of their supposed benefit to the society and the economy," he said.
Mr McCreevy said his Department was working closely with the Revenue to investigate information issues with a view to producing possible solutions.
"The challenge is twofold: the first is to identify the optimal manner of obtaining the information that is required to monitor and cost existing reliefs, and the second is to obtain such information with due regard to not overburdening compliant taxpayers."
