Patrick Bolton, Marcin Kacperczyk Pricing carbon is a cost-effective instrument to achieve emission reduction targets. The introduction of a substantial tax on industrial carbon emissions could be an important part of future climate policy. Tax rate proposals of €100 or €200 per tonne of CO 2e in 2030 on top of the carbon price in the EU Emissions Trading System (EU ETS) are not uncommon. However, implementing a national carbon tax has proven to be politically difficult (Stiglitz 2019, Dolphin et al. 2020). A key concern is that such a tax may hurt domestic industrial activity. Another concern is carbon leakage – i.e. the emission reduction achieved domestically could (partly) be offset by an increase in carbon emissions in foreign countries with more favorable tax regimes.