There has been much media coverage in recent days and weeks regarding corporation tax in Ireland and in particular the windfall revenues from this tax head accruing to State and the uses to which it could or should be put – a ‘rainy day’ fund or infrastructure development etc.  The media reports have touched on the extent of concentration among the companies that pay most of the country’s corporation tax.  This article presents accurate estimates of the extent of the concentration in net corporation tax receipts in each of the years 2022, 2021, 2020 and 2019 based on publicly available data from Revenue (for example, the latest available publication showing the 2022 data (Table 6, p. 9 of 34) is available here).

The Revenue data are grouped but the formula developed by Drs. Esmaiel Abounoori and Pat McCloughan (when they overlapped at the University of Liverpool at the beginning of the Millennium) enables accurate estimation of the Gini Coefficient of Inequality given grouped data (their technique is derived and outlined in a publication in Applied Economics Letters in 2003 available here).  (Esmaiel Abounoori is currently Professor of Econometrics and Social Statistics at the Semnan University in Iran.)

The Gini Coefficient is an easily understood measure of inequality used by economists and commentators in the social sciences more widely: the extreme cases are zero and unity, implying perfect equality and complete inequality or concentration respectively.  In practice, the Gini Coefficient varies in-between the extreme values with higher values indicating more inequality.

According to the latest Revenue publication cited above, corporation tax (CT) was the second largest tax head in Ireland, with €22.6 billion in net receipts transferred to the Exchequer in 2022, equivalent to 27.5% of total tax receipts in that year. Net CT receipts grew by 48% during 2021-2022, strongly surpassing growth in general economic activity in Ireland in the same period.

In terms of ownership, net receipts from foreign-owned multinational enterprises in 2022 were €19,579m or 86.5% of the total, while the corresponding figures for Irish-owned multinationals and non-multinationals were €928m (4.1% of net receipts) and €2,135m (9.4% of net receipts) respectively. During 2011-2022, the proportion of all net receipts in respect of corporation tax from the 10 largest corporates in Ireland rose from 39% to 57%.

Of the 77,136 companies who paid corporation tax to Revenue in 2022, 171 or 0.2% paid €17,951m of the total €22,645m or over 79% of the total net payments. That’s pretty high concentration by any comparison.  But the Gini Coefficient provides a more intuitive and better understood measure of inequality/concentration.

For the past four years (2019-2022 inclusive), Revenue has provided a distribution of net CT payments to Ireland, enabling estimation of the Gini Coefficient for each of those years.

Since the data are grouped, one might think that estimation of the Gini Coefficient would be complex or tricky to achieve. However, a method for accurate estimation of the Gini Coefficient given grouped data can be applied to the Revenue data (namely the technique due to Abounoori and McCloughan cited above).

Applying the technique to the (publicly available) Revenue grouped data yields the following estimates for the Gini Coefficient in respect of inequality in net CT receipts:

• 0.9605 in 2022;
• 0.9644 in 2021;
• 0.9682 in 2020;
• 0.9667 in 2019.

Since the Gini Coefficient generally ranges between zero (no inequality or perfect equality) and 1 (complete inequality) then these numbers imply extremely high inequality or concentration of net CT receipts in a small number of companies.

By way of comparison, the Gini Coefficient of income inequality in Ireland was 0.28 (or 28%) in 2022 (according to the Central Statistics Office, available here) and the Gini Coefficient of wealth inequality (which is generally expected to be higher than income inequality) is estimated at 31.4% for Ireland in 2023 (according to data from World Population Review) (available here) (with the caveat that measurement of wealth inequality is generally more challenging than that of income inequality).

In summary, inequality as measured by the Gini Coefficient is extremely high in regard to net corporation tax receipts in Ireland – the numbers bulleted above are accurate given the Revenue data and the Abounoori-McCloughan estimator for grouped data published in 2003 and it will be interesting to track this measure of inequality/concentration as further data become available in the coming years.