Dr. Barra Roantree:

It would be welcome. That type of analysis is carried out in other countries. It provides very useful information for legislators, as the Deputy has set out. It can be conceptually difficulty. The whole area of tax expenditures is fraught because it is both conceptually and empirically difficult to work out how much many of these things are costing. The reason for this is often that these are measured relative to a benchmark and it is not always clear what the benchmark should be. An example that comes up frequently is in the area of the taxation of pensions. What should be considered the benchmark in that regard? There is no right answer to that question. There are a number of possible answers, some of which are more credible than others. Ultimately, setting out what should be considered a tax relief in the context of pensions depends on how you think about the benchmark system and what you consider a neutral system to compare it to.

It would be welcome to see more work on tax gaps. It is something that could form part of the work of a new tax expenditure unit, or would be related to, if one were to be established. As the committee well knows, having studied the issues through multiple reports, it is in many cases a thorny issue to identify how much a tax expenditure costs and getting the estimate can be difficult. That does not mean we should not try or have a good, credible process for trying to get that estimate.