Can environmental protection tax aggravate illegal pollution discharge of heavy polluting enterprises?

This paper mainly studies the impact of environmental protection tax (EPT) on the illegal emission behaviors of heavy polluting enterprises. Based on the real-time data from the nearest air monitoring points, this paper calculates the day-night difference of PM_2.5 to measure whether there are illegal emission behaviors. And, difference in difference method (DID) is used based on the quasi-natural experiment of EPT. First, the baseline DID results show that EPT reduces day-night difference of PM_2.5, and inhibits illegal emissions. Second, the influence paths results show that EPT can inhibit illegal emission by increasing innovation, environmental responsibility performance, and environmental penalty cost, and EPT aggravate illegal emissions by increasing environmental costs and environmental corruption. Third, the influence of different pollutant pricing on illegal emissions is further analyzed. The effect of air pollutant pricing on illegal emissions is inhibited first and then promoted, while higher water pollutant pricing will aggravate illegal emissions. This paper provides enlightenment on adjusting EPT policy for local governments to curb illegal emissions, and provides an economic explanation for the differences of illegal pollution discharge in different places.