I am informed by the Revenue Commissioners that the relevant historical information available relates to the income tax liability of the top 4% of income earners as derived from income tax returns filed for the income tax year 2007, the latest year for which such information is available. For that year it is estimated that the top 4% of income earners were liable for 42.4 % of the total amount of income tax due for that year.
The estimates for 2008, 2009 and 2010, based on Revenue's latest projections, are 44.5%, 45.2% and 48% respectively. The figures are estimates from the Revenue tax-forecasting model using actual data for the year 2007, adjusted as necessary to take account of the most recent data available for income and employment trends for the years in question. They are therefore provisional and likely to be revised. It should be noted that a married couple who has elected or has been deemed to have elected for joint assessment is counted as one tax unit. The information requested by the Deputy in relation to the next 4% and every successive cohort is not readily available and could not be obtained without conducting a protracted examination of the Revenue Commissioners' records.