Just 20 multinational companies paid half of all the Corporation Tax received by the State last year, and the top ten multinational companies here paid 40% of all the Corporation Tax.
Figures from the Department of Finance, released following a parliamentary question from Fianna Fáil finance spokesperson Michael McGrath, confirm the highly-concentrated nature of Corporation Tax payments, with a large part of the payments coming from a handful of companies.
And the figures show an increasing dependence on a small group of companies in the years since 2010.
As yet there is no breakdown of the share of tax paid by foreign-owned multinationals, and Irish-owned multinationals, such as CRH or Smurfitt Kappa.
The Department of Finance said the Revenue Commissioners in the process of enhancing their data in respect of the share of Corporation Tax associated with both foreign owned and Irish owned multinational companies.
"When completed over the coming months, this exercise should improve the accuracy of data produced in respect of multinational tax".
However, it said that "the enhancements to date indicate that the share of Corporation Tax receipts for the years in question (2010-2016) is generally around 80% for foreign-owned multinational companies".
Mr McGrath TD said "Across all the tax headings, Ireland is expected to collect €50.6bn in tax in 2017 with corporation tax anticipated to account for €7.7bn (or 15%) of the total. If the same concentration in Corporation Tax receipts occurs in 2017, then 6% of the country’s overall tax take from all sources will come from just ten multinational groups".
Information from the Revenue Commissioners "Large Cases Division", which deals with the biggest corporate taxpayers, shows that in 2015 10,190 companies paid €6.8 billion in Corporation Tax – 80.5% of the total collected.
Incomplete data for 2016 show the percentage from paid by the largest firms rose to 82.1%.
Mr McGrath said "The data underlines the highly concentrated nature of our corporation tax receipts and certainly raises important issues about the level of dependence we have on the amount of tax paid by a very small number of companies.
"While our success in attracting these companies is a huge positive for the Irish economy, we need to recognise that being dependent on so few companies for such a large slice of our corporation tax take does expose us to a potential vulnerability.
"This is part of the reason why Fianna Fáil proposed the establishment of a 'rainy day fund' so that a portion of receipts from what is a volatile tax heading could be put aside as a buffer to cushion us against a future economic downturn."
A number of external and internal agencies, including the Fiscal Advisory Council, have been critical of permanent increases in government spending that have been paid for by revenues from a highly concentrated and volatile source, namely Corporation Tax.
These figure highlight the concern that one or two of the top ten corporate taxpayers have a bad year, the loss of revenue could materially impact on the government’s budget arithmetic.