(A03) Optimal Taxation and Field Experiments

In the past two decades of public economics research, a theoretical framework has been developed to incorporate causal effect estimates from empirical studies into traditional tax and social security policy theories to obtain quantitative insights into socially desirable policies. However, existing research has not clarified the relationships among models in different policy domains, such as tax and social security, and there remain policy domains wherein these models have not been applied.

This study addresses the following two issues. First, in the development of optimal tax theory, we devise a model that systematically organizes how we should design the progressivity of tax rates and deductions from the parameters of household behavior and income distribution that can be estimated from tax administrative data. In the field experiment on tax collection practices, we conduct a randomized controlled experiment (RCT) to estimate the effects of tax collection measures in cooperation with local governments that desire to improve their tax collection rates and reduce their administrative burden, and discuss the results based on the theoretical framework.