The Double Irish arrangement was a base erosion and profit shifting (BEPS) corporate tax avoidance tool used mostly by United States multinationals since the late 1980s to avoid corporate taxation on non-U.S. profits. It was the largest tax avoidance tool in history and by 2010 was shielding US$100 billion annually in US multinational foreign profits from taxation, and was the main tool by which US multinationals built up untaxed offshore reserves of US$1 trillion from 2004 to 2018. Traditionally, it was also used with the Dutch Sandwich BEPS tool; however, 2010 changes to tax laws in Ireland dispensed with this requirement.

Base erosion and profit shifting (BEPS) refers to corporate tax planning strategies used by multinationals to "shift" profits from higher-tax jurisdictions to lower-tax jurisdictions or no-tax locations where there is little or no economic activity, thus "eroding" the "tax-base" of the higher-tax jurisdictions using deductible payments such as interest or royalties. For the government, the tax base is a company's income or profit. Tax is levied as a percentage on this income/profit. When that income / profit is transferred to a tax haven, the tax base is eroded and the company does not pay taxes to the country that is generating the income. As a result, tax revenues are reduced and the country is disadvantaged. The Organisation for Economic Co-operation and Development (OECD) define BEPS strategies as "exploiting gaps and mismatches in tax rules". While some of the tactics are illegal, the majority are not. Because businesses that operate across borders can utilize BEPS to obtain a competitive edge over domestic businesses, it affects the righteousness and integrity of tax systems. Furthermore, it lessens deliberate compliance, when taxpayers notice multinationals legally avoiding corporate income taxes. Because developing nations rely more heavily on corporate income tax, they are disproportionately affected by BEPS.