Marrying into a Tax Bracket: A New Approach to Estimating Tax Elasticities

尽管经济学家长期以来一直对估计税收弹性感兴趣，但很少有研究提供分类估计。评估税收弹性的典型方法通常依赖于针对特定人口群体的改革，从而为该特定人口群体提供衡量标准(例如，通过研究劳动力供应对最高收入税率下调的反应)。由于缺乏对基本收入、家庭收入等级和性别的税收弹性的单独估计，在最优家庭税制方面留下了很大的争议空间，许多经济学家认为，对收入进行联合征税阻碍了女性融入劳动力市场。法国所得税制度的设计和住房和个人人口档案(FIDELI)的提供，为对收入分配的多个点以及初级和次级收入者分别进行更详细的税收弹性估计提供了一个独特的新机会。该策略利用法国边际税制的阶梯式设计，构建了一个准实验。由于这些措施，婚前家庭收入略有不同的夫妇在结婚后属于不同的税级。经济学理论预测，边际税级定义了人们对工作“报酬”的看法。家庭收入为5.5万欧元的夫妇婚后将面临30%的边际税率，与共同收入为54900欧元(少100欧元)的家庭成员相比，他们继续工作的动机可能会更弱，婚后将面临11%的边际税。弹性是衡量选择对这些不同税率的敏感性的指标--这很可能取决于基线收入、排名(养家糊口的人与否)和性别。为了将税收的效果与可能影响劳动力供应决策的其他因素分开，策略是比较夫妇在税率跃升的家庭收入门槛水平之前和之后。其假设是，对起征点右侧和左侧的观察结果之间的任何社会经济特征差异都是连续的，两个群体总体上唯一的差异是税率。虽然拟议的战略可以用来分析与劳动力无关的税收弹性的边际，例如生育率或离婚率的弹性，但政策相关性最大的边际可能是第二收入劳动力市场的参与度。后者对于评估共同家庭税制阻碍妇女融入劳动力市场的共同主张的有效性很重要，第二收入比率比第二收入者在个人纳税下将面临的第二收入比率更具说服力。由于婚姻对所有收入的人都适用，而且有许多收入门槛需要评估，该方法将提供比文献更广泛和更普遍的证据基础。后者通常依赖于特殊的所得税改革，在特定的政策和宏观经济背景下影响到特定的十分之一的分配。Fideli的纵向形式和使用婚姻作为准实验来源将提供更多的分类估计，同时减少宏观经济或政治偏见的风险。

Despite economists long-standing interest in estimating tax elasticities, there are few studies providing disaggregated estimates. The typical approach to estimating tax elasticity typically relies on reforms that target a particular demographic group and thus provide measures for that particular demographic group (for example, by studying the response of labour supply to cuts in top-income tax rates). The lack of separate estimates of tax elasticity by base income, household income rank and gender leaves much room for controversy about optimal household taxation with many economists arguing that joint taxation of income hinders the integration of women into the labour market. The design of the income tax system in France and the availability of the Housing and Individual Demographic Files (Fideli), provide a unique new opportunity for more disaggregated estimations of tax elasticities, across multiple points of the income distribution and for primary and secondary earners separately. The strategy makes uses of the stepped design of the French marginal tax schedule to construct a quasi-experiment. Because of those steps, couples with marginally different household incomes immediately before marriage fall into different tax brackets after marriage.Economic theory predicts that the marginal tax bracket defines the perception of how much work "pays". Couples with a household income of 55000euro face a marginal tax rate of 30% after marriage, and will likely to be less incentivised to continued work than members of households with a joint income of 54900 euro (100 euro less), facing a marginal tax of 11% after marriage. The elasticity is a measure of the sensitivity of choices to those different tax rates - which may be very well depend on baseline income, rank (breadwinner or not) and gender. To isolate the effect of the tax from other factors that may influence the labour supply decision, the strategy is to compare couples just before and just after the threshold level of household income at which the tax rate jumps. The assumption is that any differences in socio-economic characteristics between observations to the right and left of the threshold are continuous and that the only difference between the two groups in the aggregate is the tax rate. Although the proposed strategy can be used to analyse margins of non-labour related tax elasticities, such as fertility or divorce rate elasticities, perhaps the margin of greatest policy relevance is that of second income labour market participation. The latter is important for assessing the validity of the common claim that joint household taxation hampers women's labour market integration with second income rates that are more dissuasive compared to those second earners would face under individual taxation. Since marriage is available to all incomes and there are many income thresholds to assess, the method will provide a broader and more generalizable evidence base than the literature. The latter typically relies on idiosyncratic income tax reforms, affecting a particular decile of the distribution in a specific policy and macroeconomic context. Fideli's longitudinal form and the use of marriage as quasi-experimental source will provide more disaggregated estimates while reducing the risk of macroeconomic or political bias.