关键词: 个人所得税, 最高边际税率, 最优非线性所得税

Abstract: As a tool of adjusting income distribution and optimizing resources allocation, The marginal tax rate of the personal income tax has attracted extensive attention. Thereinto, the current highest marginal tax rate of 45% has sparked great controversy. This paper, in the light of China's reform of the personal income tax, uses the optimal non-linear income tax theory of Saez to calculate and analyze the highest marginal tax rate and its influencing factors in terms of different income distributions and social welfare functions, with family as its tax unit, annual income the study object and salary the example. It suggests that there is certain room for lowering the current rate of 45% as the highest marginal tax rate to strike a balance between efficiency and equity. Saez's idea is generic and provides references to the establishment of China's personal income tax system that unifies synthesis and classification.

Key words: Personal Income Tax, Highest Marginal Tax Rate, Optimal Non-linear Income Tax