The international tax system is a pillar of the post-war economic order, but it faces major challenges with the rise of global value chains, digitalization, and tax avoidance. Debates over international tax reform usually occur within a small epistemic community of experts and technocrats. In this article, we step outside this restricted circle to assess the sources of bottom-up legitimacy and support for the rules that govern where multinationals must report profits and which governments are entitled to tax those profits. We conduct survey experiments in Brazil, France, and the United States to assess mass attitudes toward the allocation of the tax base across countries. We find that people’s views clash with the core principles of the current regime, but are aligned with reform proposals that allocate more taxing rights to market jurisdictions. These findings are strikingly consistent across three countries and three distinct studies. At first glance, the consistency of attitudes across countries could spell good things for international cooperation in this arena. However, we also find a significant level of “home bias” in the public’s views on tax allocation. These results shed new light on the legitimacy of tax reform and on the prospects for cooperation in a key area of international economic relations.