Energy efficiency suppression and spatial spillover effect: a quasi-natural experiment based on China's environmental protection tax law

The environmental protection tax law (EPTL) is China's inaugural formally legislated market-based environmental tax regime. Whether the EPTL can improve green total factor energy efficiency (GTFEE) is of great importance for China's sustainable development. Utilizing a sample of China's 284 prefecture-level cities from 2015 to 2019 and the difference-in-differences method, this study explores the impact of China's environmental protection tax law (EPTL) on green total factor energy efficiency (GTFEE). Results show that: (1) The EPTL exerts a significant negative impact on GTFEE, a conclusion reinforced by a series of robustness checks; (2) two potential mechanisms are reduced green technology innovation and shifted industrial structure; (3) heterogeneity analysis underscores that the negative effects are more significant in eastern regions, old industrial cities, and cities under high fiscal pressure; and (4) based on the spatial difference-in-differences method, the subsequent analysis reveals a negative spatial spillover effect of the EPTL on GTFEE of neighboring cities. Derived from the above conclusions, this study provides policy recommendations for the long-term formulation of the EPTL.