The link between income inequality and progressive taxation has long been considered a fundamental normative foundation for income tax progressivity. This paper furnishes necessary and sufficient conditions on primitives, in terms of the elasticity of income with respect to ability, under which various subclasses of progressive taxes are inequality reducing. The distributional effects of progressive income taxation are decomposed into two conditions on the wage elasticity of income, the tax rate effect and the subsidy effect, each capturing different aspects of the transition between before-tax and after-tax income distributions. The results confer a degree of useful flexibility to the theory, in that they allow the analyst to expand the universe of consumer preferences by suitably restricting the set of marginal-rate progressive taxes. As an illustration of the results’ practical implications, we provide a precise characterization of the subclass of (progressive) taxes that are inequality reducing for the constant elasticity of substitution (CES) and the quasi-linear utility functions.

长期以来，人们一直认为收入不平等与累进税之间的联系是所得税累进性的基本规范基础。本文根据收入相对于能力的弹性为原始数据提供了必要和充分的条件，在这些条件下，累进税的各种子类别正在减少不平等现象。将累进所得税的分配效应分解为收入的工资弹性的两个条件，即税率效应和补贴效应。，每个都捕获了税前和税后收入分配之间过渡的不同方面。结果为该理论提供了一定程度的有用灵活性，因为它们允许分析人员通过适当限制边际税率累进税的设置来扩大消费者的偏好范围。为了说明结果的实际含义，我们对（累进）税的子类进行了精确的刻画，对于不变的替代弹性（CES）和准线性效用函数，这些税收不等式正在减少。