EU corporate tax policy has long consisted solely in eliminating fiscal barriers. This changed after the financial and Eurozone crises when the European Commission proposed ‘market-correcting’ provisions to increase tax transparency and ‘fairness’, which were partially adopted by the Council. Analyses of EU responses to the crisis have largely ignored taxation issues. This article fills this gap and explains the substantive re-orientation of EU corporate tax policy through the concept of politicization. Based on 19 expert interviews, it details the politicization process of corporate taxation resulting from changes in global governance, media tax scandals, and the work of non-governmental organizations (NGOs). Through the politicization dynamic, new institutional and discursive opportunities were exploited by the European Commission, Parliament and NGOs to induce policy change. We explore this reciprocal interaction between social forces and supranational actors to demonstrate that ‘politicization at the top’ can facilitate a more progressive deepening of European integration.