中文摘要
本文首次对估计应税收入弹性（ETI）的两种主要方法（税制改革法与聚束法）进行正式比较；ETI是自Feldstein（1999）以来公共财政文献中的一个核心参数。我们使用一套新的中国行政税收面板数据，并利用中国累进的月度工资所得税税表以及2011年的一项税制改革，记录了这两种方法所得ETI估计值的两个关键差异。第一，税制改革法的ETI估计值随时间呈凹形上升，而聚束法的ETI估计值则稳定得多。第二，税制改革法的ETI估计值（长期约为4）远大于聚束法的ETI（约为0.5），且这一差异在统计上显著。为解释这些事实，我们构建了一个简单模型：个体在每一期都有一定概率在不支付其他成本的情况下永久改变工作时间，但可以通过支付额外成本临时调整工作时间。在工资率稳定的情况下，两种估计量应收敛于相同的潜在值。但在正常的工资增长下，税制改革法的估计值会收敛于真实的潜在参数，而聚束法的估计值则可能远低于真实数值。
Abstract
This paper conducts the first formal comparison of two main approaches (tax reform versus bunching approach) to estimate the elasticity of taxable income (ETI), a central parameter in the public finance literature since Feldstein (1999). Using a novel panel of administrative tax data from China and exploiting China’s progressive monthly wage income tax schedule and a tax reform in 2011, we document two key differences in the ETI estimates obtained from these two approaches. First, the tax reform ETI estimates increase concavely over time, while the bunching ETI estimates are much more stable. Second, the tax reform ETI estimates (around 4 in the long-run) are much larger than the bunching ETI (around 0.5), and the difference is statistically significant. To account for these facts, we develop a simple model where individuals in each period have some probability to permanently change hours of work without paying other costs but can temporarily adjust hours by paying additional costs. With stable wage rates, the two estimators should converge to the same underlying value. But with normal wage growth, the tax reform estimates converge to the true underlying parameter, whereas the bunching estimates can be far below the true figure.