This paper derives novel formulas for the welfare gains of any tax reform around initial (optimal or suboptimal) dynamic tax systems. We use a perturbation-based method to express these formulas in terms of easily interpretable and empirically estimable parameters: elasticities of income and...

We study the problem of optimal social insurance when agents are privately informed and the government cannot commit to a particular allocation. Contrary to the previous literature, we assume that agents' types have some persistence. We show that under some conditions it is optimal for the...