This paper examines corporate tax avoidance involving Dutch special purpose entities (SPEs), or shell companies. We use unique data of the SPEs including the origin and destination country of dividend, interest, and royalty flows passing the Netherlands. First, we present descriptive statistics of these flows which amount to 140 billion euro in 2016. Second, we collect national tax data on the corporate income tax and fiscal treatment of these flows. By combining tax parameters with bilateral flows, we can assess the potential tax gains for multinational enterprises using Dutch SPEs. We find massive tax savings for royalties when Dutch SPEs are used as an intermediate station compared to direct flows between the origin and destination country. We measure this tax gain at almost 3 billion euro in a single year. However, we do not find such tax savings for dividends and interest. We explain where we lack information and hence cannot measure possible tax gains. In regression analysis, controlling for country characteristics, we find that tax differentials partially explain the geographical patterns of income flows diverted through the Netherlands. This paper is one of the first using bilateral income flows as dependent variables instead of FDI stocks or flows.