In this paper, we consider an environment in which agents’ productivities are private information, potentially multi-dimensional, and follow arbitrary stochastic processes. We allow for arbitrary incentive-compatible and physically feasible tax schemes. We prove that it is typically Pareto...

In this paper we describe how to optimally design a disability insurance system. The key friction in the model is imperfectly observable disability. We solve a dynamic mechanism design problem and provide a theoretical and numerical characterization of the social optimum. We then propose a...

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 how Americans respond to idiosyncratic and exogenous changes in household wealth and unearned income. Our analyses combine administrative data on U.S. lottery winners with an event-study design that exploits variation in the timing of lottery wins. Our first contribution is to estimate...

In this paper, we generalize the notion of Pareto-efficiency to make it applicable to environments with endogenous populations. Two efficiency concepts are proposed, P-efficiency and A-efficiency. The two concepts differ in how they treat people who are not born. We show how these concepts...

This paper develops a model of a monetary economy in which individual firms are subject to idiosyncratic productivity shocks as well as general inflation. Sellers can change price only by incurring a real menu cost.' We calibrate this cost and the variance and autocorrelation of the...

We study optimal monetary and fiscal policy in a model with heterogeneous agents, incomplete markets, and nominal rigidities. We develop numerical techniques to approximate Ramsey plans and apply them to a calibrated economy to compute optimal responses of nominal interest rates and labor tax...

We study optimal fiscal and redistributive policies in an open economy without commitment. Due to its redistributive motives, the government's incentive to default on its external debt is affected by inequality. We show that in equilibrium the economy endogenously fluctuates between two regimes....

We propose a new business cycle theory. Firms need to randomize over firing or keeping workers who have performed poorly in the past, in order to give them an ex-ante incentive to exert effort. Firms have an incentive to coordinate the outcome of their randomizations, as coordination allows them...