Figures obtained from Revenue Commissioners by Sinn Féin show the top 10% of earners in Ireland generated a third of all income in 2016, with the highest earning 10,000 citizens in the State taking in €5.6 billion between them.
That means that, on average, 10,000 people earned over €500,000 each in gross pay.
This is the first time Revenue has published figures on gross income per individual as opposed to the taxpayer unit, e.g., a family.
The statistics show the top 1% of earners generated 11% of all income during the year.
At the other end of the scale, the bottom 50% of workers only earn around a fifth of all income.
Sinn Féin Finance Spokesperson Pearse Doherty said the figures reveal "a shocking level of income inequality at the heart of Irish society".
Mr Doherty has called for an increase in the minimum wage to €10.50 per hour.