政策门槛作为增长壁垒：来自工资税凹口的理论与证据
Policy Thresholds as Growth Barriers: Theory and Evidence from a Payroll Tax Notch
NBER Working Papers · 2026 · [{"name": "Sami Jysmä", "affiliation": []}, {"name": "Youssef Benzarti", "affiliation": []}, {"name": "Jarkko Harju", "affiliation": []}]
中文摘要
离散型政策门槛在税收和监管体系中普遍存在，可能严重扭曲行为。我们证明，作为分布内流动性壁垒的凹口(notch)会产生远超门槛本身范围的扭曲。同样的机制也会使常规双重差分(DID)估计量产生偏误，为此我们提出一种恢复因果效应的新方法。将该方法应用于一项基于企业规模的工资税凹口的废除案例，我们发现该凹口使门槛以上的企业数量减少了18%，并使受处理企业的就业、资本存量和增加值分别降低了10%，而常规双重差分估计则显示影响微乎其微。
Abstract
Discrete policy thresholds are pervasive in tax and regulatory systems and can substantially distort behavior. We show that notches acting as barriers to mobility within a distribution generate distortions extending far beyond the threshold. The same mechanism biases conventional difference-in-differences estimators, and we propose a new methodology to recover causal effects. Applying the method to the abolition of a size-based payroll tax notch, we find that the notch reduced the number of firms above the threshold by 18 percent and lowered treated firms’ employment, capital stock, and value added by 10 percent, whereas conventional difference-in-differences estimates imply negligible effects.