The relevance of tax progressivity measures to policymaking depends on whether they help assess the extent to which taxation leads to social welfare gains or losses. The social welfare implications of progressivity measures have yet to be explored adequately in the literature. This paper helps to fill this gap by proposing a social welfare function framework to derive measures of tax progressivity and explore their normative properties. Using the social welfare framework, the paper derives the Kakwani index from Sen’s social welfare function as well as a new class of progressivity measures that incorporate a distributional judgment parameter capturing inequality aversion. The paper also discusses the social welfare implications of the Suits measure of tax progressivity and develops a new measure of tax progressivity derived from the Bonferroni social welfare function. The paper derives both relative and absolute measures of tax progressivity from the social welfare function framework. The methodology developed in the paper is applied to make international comparisons of tax progressivity in 32 developed countries. The paper calculates the magnitude of welfare gains and losses due to taxation and the required social rates of return of public investments for governments to break even. This paper finds that the governments in some countries have to generate high social rates of return from their public investments to compensate for losses of social welfare from taxation. It concludes that optimizing social welfare requires designing a progressive tax system, minimizing the administrative costs of collecting taxes, and maximizing the social rates of return by efficiently investing tax revenues.

税收累进性措施与决策的相关性取决于它们是否有助于评估税收导致社会福利收益或损失的程度。渐进性措施对社会福利的影响尚未在文献中得到充分探讨。本文通过提出社会福利功能框架来推导税收累进措施并探索其规范性质，从而帮助填补这一空白。本文使用社会福利框架，从森的社会福利功能以及包括吸收不平等厌恶的分布判断参数在内的一类新的累进性测度中，得出卡克瓦尼指数。本文还讨论了西服税率累进措施的社会福利含义，并从邦费罗尼社会福利函数中得出了一种新的税率累进措施。本文从社会福利功能框架中得出了税收累进性的相对和绝对度量。本文开发的方法用于对32个发达国家的税收累进性进行国际比较。本文计算了税收带来的福利收益和损失的幅度，以及政府为达到收支平衡所需的公共投资的社会收益率。本文发现，某些国家的政府必须从其公共投资中产生较高的社会回报率，以弥补税收带来的社会福利损失。