There is, it seems to me, a very facile tendency in the Department of Finance to assume that the 'cost' of tax reliefs can easily be assessed in terms of tax foregone. For this to be true, you would have to assume that people do not alter their behaviour so as to minimise their tax exposure. We reduced CGT from 40% to 20% and the yield increased - but the lesson was totally lost on the Mandarins.
Many High Net Worth individuals own or control trading companies. Within limits, they can choose each year how much (personal) income they will pay themselves.
It is nonsense to assume that if the various reliefs were not available, these people would still choose to take income they might not need and subject it to tax that they do not wish to pay. But that is exactly what the Department of Finance does in publishing an analysis in this form.
When increasing the capital\transactional tax rates, they seem to do the same thing - i.e. to assume that an increase in CGT or CAT will produce almost a pro-rata increase in tax take, without any - or any proper- cognizance of the fact that higher tax rates mean few taxable transactions. Or perhaps I am being harsh on them - I freely admit that in matters of public sector finance I am something of a hurler on the ditch.