Optimal Taxation with Endogenous Insurance Markets

We study optimal tax policy in a dynamic private information economy with endogenous private markets. We characterize efficient allocations and competitive equilibria. A standard assumption in the literature is that trades are observable by all agents. We show that in such an environment the competitive equilibrium is efficient. The only effect of government interventions is crowding out of private insurance. We then relax the assumption of observability of consumption and consider an environment with unobservable trades in competitive markets. We show that efficient allocations have the property that the marginal product of capital is different from the market interest rate associated with unobservable trades. In any competitive equilibrium without taxation, the marginal product of capital and the market interest rate are equated, so that competitive equilibria are not efficient. Taxation of capital income can be welfare-improving because such taxation introduces a wedge between market interest rates and the marginal product of capital and allows agents to obtain better insurance in private markets. Finally, we use plausibly calibrated numerical examples to compute optimal taxes and welfare gains and compare results to an economy with a restricted set of tax instruments, and to an economy with observable trades.

Designing Optimal Disability Insurance: A Case for Asset Testing

The paper analyzes an implementation of an optimal disability insurance system as a competitive equilibrium with taxes. The problem is modeled as a dynamic mechanism design problem in which disability is unobservable. We show that an asset-tested disability system in which a disability transfer is paid only if an agent has assets below a specified maximum implements the optimum. The logic behind the result is as follows: we show that an agent who falsely claims disability has higher savings than a truly disabled agent, and an asset test prevents false claimants from receiving disability. We also evaluate welfare benefits of asset testing. For a calibrated economy, we numerically compare the optimal system to the best system without asset testing. We find that gains of asset testing are significant and equal to about 0.65% of consumption.

Efficiency with Endogenous Population Growth

In this paper, we generalize the notion of Pareto-efficiency to make it applicable to environments with endogenous populations. Two different efficiency concepts are proposed, P-efficiency and A-efficiency. The two concepts differ in how they treat people that are not born. We show how these concepts relate to the notion of Pareto efficiency when fertility is exogenous. We then prove versions of the first welfare theorem assuming that decision making is efficient within the dynasty. Finally, we give two sets of sufficient conditions for non-cooperative equilibria of family decision problems to be efficient. These include the Barro and Becker model as a special casePareto efficiency, endogenous fertility, first welfare theorem

Preference Heterogeneity and Optimal Capital Taxation

We analytically and quantitatively examine a prominent justification for capital income taxation: goods preferred by those with high ability ought to be taxed. We study an environment where commodity taxes are allowed to be nonlinear functions of income and consumption and find that, when ability is positively related to a preference for a good, optimal marginal commodity taxes on this good may be regressive: i.e., declining with income. We derive an analytical expression for optimal commodity taxation, allowing us to study the forces for and against regressivity. We then parameterize the model to evidence on the relationship between skills and preferences and examine the quantitative case for taxes on future consumption (saving). The relationship between skill and time preference delivers quantitatively small, generally regressive capital income taxes and would justify only a fraction of the prevailing level of capital income taxation.

Preference Heterogeneity and Optimal Capital Income Taxation

We analytically and quantitatively examine a prominent justi.cation for capital income taxation: goods preferred by those with high ability ought to be taxed. We study an environment where commodity taxes are allowed to be nonlinear functions of income and consumption and .nd that, when ability is positively related to a preference for a good, optimal marginal commodity taxes on this good may be regressive: i.e., declining with income. We derive an analytical expression for optimal commodity taxation, allowing us to study the forces for and against regressivity. We then parameterize the model to evidence on the relationship between skills and preferences and examine the quantitative case for taxes on future consumption (saving). The relationship between skill and time preference delivers quantitatively small, generally regressive capital income taxes and would justify only a fraction of the prevailing level of capital income taxation.JCKNMLNHOGJE

Optimal Dynamic Taxes

We study optimal labor and savings distortions in a lifecycle model with idiosyncratic shocks. We show a tight connection between its recursive formulation and a static Mirrlees model with two goods, which allows us to derive elasticity-based expressions for the dynamic optimal distortions. We derive a generalization of a savings distortion for non-separable preferences and show that, under certain conditions, the labor wedge tends to zero for sufficiently high skills. We estimate skill distributions using individual data on the U.S. taxes and labor incomes. Computed optimal distortions decrease for sufficiently high incomes and increase with age.

A Theory of Liquidity and Regulation of Financial Intermediation

This paper studies a mechanism design model of financial intermediation. There are two informational frictions: agents receive unobservable shocks and can participate in markets by engaging in trades unobservable to intermediaries. Without regulations, intermediaries provide no risk sharing because of an externality arising from arbitrage opportunities. We identify a simple regulation -- a liquidity requirement -- that corrects such an externality by affecting the interest rate on the markets. We characterize the form of the optimal liquidity adequacy requirement for a general class of preferences. We show that whether markets underprovide or overprovide liquidity, and whether a liquidity cap or a liquidity floor should be used depends on the nature of the shocks that agents experience. Moreover, we prove that the optimal liquidity adequacy requirement implements a constrained efficient allocation subject to unobservable types and trades. We provide closed form solutions for the optimal liquidity requirement and welfare gains of imposing such requirements for two important special cases. In contrast with the existing literature, the necessity of regulation does not depend on exogenous incompleteness of markets for aggregate shocks.