Tax avoidance by multinationals made headlines in 2021 with the international agreement on reforming the taxation of multinational enterprises. While the importance of the issue is no longer debated, little is known about which firms are most likely to engage in tax avoidance. It turns out that the complexity of the ownership structure of the subsidiaries of a multinational firm – be it a flat structure in which headquarters directly owns its subsidiaries or a more complex organization involving chains of ownership – plays an important role in these schemes: only sufficiently complex multinationals shift profits from their high-tax subsidiaries to those located in low-tax countries.