Abstract Since 2016, multinationals with a revenue over EUR 750 million have to submit country-by-country reports to tax authorities to deter tax avoidance. Using a regression discontinuity design, we provide evidence for an increase in affected multinationals’ effective tax rates. However, the most aggressive multinationals with known tax haven presence were only moderately affected. The effect is mainly driven by medium-aggressive firms, which achieved low effective tax rates without tax haven affiliates to shift profits to. The policy was thus effective in combating some tax avoidance but profit shifting to tax havens remains an issue, explaining the push for further policy measures including the global minimum corporate tax rate. JEL codes: F23, H25, H26