Technology is being harnessed to redefine traditional business models and provide new ways for buyers and sellers to interact both locally and globally. The result has been the emergence of a handful of firms—the so-called tech giants—that are capitalizing on first mover advantages and network externalities to boost profitability, capture market share, and turn themselves into the world’s most highly valued companies. They have inevitably captured the attention of policymakers, and in the realm of international taxation, the debate has coalesced around a number of issues that are driving the debate over whether and how countries should be able to tax the returns to highly digitalized multinational businesses (IMF 2014, 2019). More generally, an increasing number of firms are digitaliz-ing, leading to several issues that raise or intensify challenges for the international tax system.

Why Reform Is Needed and How It Could Be Designed