When in Doubt, Tax More Progressively? Uncertainty and Progressive Income Taxation
研究了参数不确定性如何影响最优所得税政策，发现不确定性使税收更累进，高低收入家庭边际税率差距扩大5.5个百分点，主要源于工资过程的不确定性。
ABSTRACT We study the optimal income tax problem under parameter uncertainty about household preferences and wage dynamics. We derive conditions characterizing how such uncertainty affects optimal tax policy. To quantify the effect, we estimate a life‐cycle model using US data and a Bayesian approach. Parameter uncertainty makes the optimal tax more progressive, increasing the marginal tax rate gap between high‐ and low‐income households by 5.5 percentage points. This effect is primarily driven by uncertainty about the wage process. We also find that parameter uncertainty imposes sizable welfare costs through the income tax channel alone.