Ireland has been labelled as a tax haven or corporate tax haven in multiple financial reports, an allegation which the state has rejected in response. Ireland is on all academic "tax haven lists", including the , and tax NGOs. Ireland does not meet the 1998 OECD definition of a tax haven, but no OECD member, including Switzerland, ever met this definition; only Trinidad & Tobago met it in 2017. Similarly, no EU–28 country is amongst the 64 listed in the 2017 EU tax haven blacklist and greylist.
In September 2016, Brazil became the first G20 country to "blacklist" Ireland as a tax haven.
Ireland's base erosion and profit shifting (BEPS) tools give some foreign corporates of 0% to 2.5% on global profits re-routed to Ireland via their tax treaty network. Ireland's aggregate for foreign corporates is 2.2–4.5%. Ireland's BEPS tools are the world's largest BEPS flows, exceed the entire Caribbean system, and artificially inflate the US–EU trade deficit. Ireland's tax-free QIAIF & L–QIAIF regimes, and Section 110 SPVs, enable foreign investors to avoid Irish taxes on Irish assets, and can be combined with Irish BEPS tools to create confidential routes out of the Irish corporate tax system. As these structures are OECD–whitelisted, Ireland's laws and regulations allow the use of data protection and data privacy provisions, and opt-outs from filing of public accounts, to obscure their effects. There is arguable evidence that Ireland acts as a , fostering tax strategies.
Ireland's situation is attributed to arising from the historical U.S. "worldwide" corporate tax system, which has made U.S. multinationals the largest users of tax havens, and BEPS tools, in the world. The U.S. Tax Cuts and Jobs Act of 2017 ("TCJA"), and move to a hybrid "territorial" tax system, removed the need for some of these compromises. In 2018, IP–heavy S&P500 multinationals guided similar post-TCJA effective tax rates, whether they are legally based in the U.S. (e.g. Pfizer), or Ireland (e.g. Medtronic). While TCJA neutralised some Irish BEPS tools, it enhanced others (e.