Evaluating the Impact of the 2021 Plastic Carrier Bag Charge Increase in England:Evidence from a Synthetic DiD Approach

Sammanfattning

This study examines whether the 2021 increase in England’s single-use plastic carrier bag charge, from 5 pence to 10 pence, generated an additional reduction in plastic bag consumption. While previous research shows that the initial introduction of plastic bag levies can produce substantial behavioral change, less is known about the effect of increasing an already established environmental charge. Using annual plastic bag consumption data for England from DEFRA and comparable European data from Eurostat for 2018–2023, the study estimates the effect of the reform using Synthetic Difference-in-Differences (SDID) as the primary empirical strategy. In addition, a Synthetic Control Method (SCM) in conjunction with a cross-sectional Difference-in-Differences regression were included as robustness checks, providing additional credibility to our results. The main SDID results show no statistically significant reduction in plastic bag consumption following the 2021 reform. The estimated treatment effect is small and statistically insignificant, with the conclusion remaining unchanged when excluding 2020 to account for potential COVID-19-related disruption. These findings suggest that the 2021 increase may have produced limited additional behavioral adjustment, possibly due to much of the extensive-margin response having already occurred following the 2015 charge. Additionally, the results point to the potentially diminishing marginal effects of repeated environmental pricing interventions.