The incidence of tax and other policy changes depends on their impact on equilibrium wages. In a standard model of labor supply, the impact of wage changes on a worker’s welfare equals current labor supply times the induced wage change. Worker heterogeneity implies that wage changes vary across workers. In this context, in order to identify welfare effects one needs to identify the causal effect of policy changes on wages conditional on baseline labor supply and wages.

This paper characterizes identification of such outcome-conditioned causal effects for general vectors of endogenous outcomes. Even with exogenous policy variation, outcome-conditioned causal effects are only partially identified for outcome vectors of dimension larger than one. We provide assumptions restricting heterogeneity of effects just enough for point-identification and propose corresponding estimators.

This paper then applies the proposed approach to analyze the distributional welfare impact (i) of the expansion of the Earned Income Tax Credit (EITC) in the 1990s, using variation in state supplements in order to identify causal effects, and (ii) of historical changes of the wage distribution in the US in the 1990s. For the EITC, we find negative welfare effects of depressed wages as a consequence of increased labor supply, in particular for individuals earning around $20,000 per year. Looking at historical changes, we find modest welfare gains rising linearly with earnings.

税收和其他政策变化的发生取决于它们对均衡工资的影响。在劳动力供给的标准模型中，工资变动对工人福利的影响等于当前劳动力供给乘以诱发的工资变动。工人异质性意味着工资变化因工人而异。在这种情况下，为了确定福利影响，需要确定以基线劳动力供给和工资为条件的政策变化对工资的因果影响。

本文描述了对内生结果的一般向量的这种以结果为条件的因果效应的识别。即使有外生的政策变化，对于维度大于 1 的结果向量，也只能部分识别出以结果为条件的因果效应。我们提供了限制效应异质性的假设，足以进行点识别，并提出相应的估计量。

然后，本文应用所提出的方法来分析分配福利的影响 (i) 1990 年代收入所得税抵免 (EITC) 扩张的影响，使用国家补助金的变化来确定因果关系，以及 (ii) 历史1990 年代美国工资分配的变化。对于 EITC，我们发现劳动力供应增加导致工资下降对福利产生负面影响，尤其是对于年收入约 20,000 美元的个人。回顾历史变化，我们发现适度的福利收益与收益呈线性增长。