The State's fiscal watchdog has estimated that almost half of the corporation tax collected by the State is paid by three multinationals.
In 2024, these large companies paid around €13 billion or 46% of corporation tax, according to the Irish Fiscal Advisory Council.
While the organisation has not named the three multinationals, they are understood to be Apple, Microsoft and pharmaceutical group Eli Lilly.
The Irish Fiscal Advisory Council said that corporation tax almost doubled between 2021 and 2024, even when back taxes paid by Apple were excluded.
The council said this sharp rise was largely driven by the increased payments from the top three players.
It is estimated that the two technology companies, Apple and Microsoft, paid the equivalent of almost 40% of total corporation tax receipts.
Irish Fiscal Advisory Council economist Brian Cronin said the "research highlights how reliant Ireland’s corporation tax has become on just three companies".
He added: "These companies continue to perform strongly, but their profits and the taxes they pay remain subject to significant uncertainty.
"As a result, corporation tax receipts could be substantially higher or lower than current levels in the medium term."
It is expected that profits from Apple and Microsoft will increase due to advances in artificial intelligence and growing demand for their products and services.
In the pharmaceutical sector, Eli Lilly is likely to continue to benefit from a surge in demand for weight-loss and diabetes medicines.
