This report examines the evolution of harmful corporate tax practices in recent years, as well as the development of blacklists intended to identify such practices. First, it shows that harmful tax practices are no longer confined to easily identifiable jurisdictions known for aggressive tax policies. Second, it finds that current blacklists—although they may be linked to potentially effective sanctions—are generally too limited in scope to produce significant economic effects. Finally, the report proposes enhanced criteria for constructing blacklists of harmful tax regimes. In particular, it argues that introducing a quantitative criterion based on effective tax rates is essential to account for the recent evolution of harmful tax competition.