Journal Article
We consider a standard New Keynesian model of a small open economy with nominal rigidities and study optimal capital controls. Consistent with the Mundellian view, we find that the exchange rate regime is key. However, in contrast with the Mundellian view, we find that capital controls are desirable even when the exchange rate is flexible. Optimal capital controls lean against the wind and help smooth out capital flows.
Download paperWe show that even when the exchange rate cannot be devalued, a small set of conventional fiscal instruments can robustly replicate the real allocations attained under a nominal exchange rate devaluation in a dynamic New Keynesian open economy environment. We perform the analysis under alternative pricing assumptions—producer or local currency pricing, along with nominal wage stickiness; under arbitrary degrees of asset market completeness and for general stochastic sequences of devaluations. There are two types of fiscal policies equivalent to an exchange rate devaluation—one, a uniform increase in import tariff and export subsidy, and two, a value-added tax increase and a uniform payroll tax reduction. When the devaluations are anticipated, these policies need to be supplemented with a consumption tax reduction and an income tax increase. These policies are revenue neutral. In certain cases equivalence requires, in addition, a partial default on foreign bond holders. We discuss the issues of implementation of these policies, in particular, under the circumstances of a currency union.
We consider a dynamic Mirrlees economy in a life-cycle context and study the optimal insurance arrangement. Individual productivity evolves as a Markov process and is private information. We use a first-order approach in discrete and continuous time and obtain novel theoretical and numerical results. Our main contribution is a formula describing the dynamics for the labour-income tax rate. When productivity is an AR(1) our formula resembles an AR(1) with a trend where: (i) the auto-regressive coefficient equals that of productivity; (ii) the trend term equals the covariance productivity with consumption growth divided by the Frisch elasticity of labour; and (iii) the innovations in the tax rate are the negative of consumption growth. The last property implies a form of short-run regressivity. Our simulations illustrate these results and deliver some novel insights. The average labour tax rises from 0% to 37% over 40 years, whereas the average tax on savings falls from 12% to 0% at retirement. We compare the second best solution to simple history-independent tax systems, calibrated to mimic these average tax rates. We find that age-dependent taxes capture a sizable fraction of the welfare gains. In this way, our theoretical results provide insights into simple tax systems.
We develop a theory of optimal estate taxation in a model where bequest inequality is driven by differences in parental altruism. We show that a wide range of results are possible, from positive taxes to subsidies, depending on redistributive objectives implicit in the cardinal specification of utility and social welfare functions. We propose a normalization that is helpful in classifying these different possibilities. We isolate cases where the optimal policy bans negative bequests and taxes positive bequests, features present in most advanced countries.
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When the zero lower bound on nominal interest rates binds, monetary policy cannot provide appropriate stimulus. We show that, in the standard New Keynesian model, tax policy can deliver such stimulus at no cost and in a time-consistent manner. There is no need to use inefficient policies such as wasteful public spending or future commitments to low interest rates.
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The paper shows that time-consistent, imperfectly targeted support to distressed institutions makes private leverage choices strategic complements. When everyone engages in maturity mismatch, authorities have little choice but intervening, creating both current and deferred (sowing the seeds of the next crisis) social costs. In turn, it is profitable to adopt a risky balance sheet. These insights have important consequences, from banks choosing to correlate their risk exposures to the need for macro-prudential supervision.
Download paperWe study efficient non-linear taxation of labour and capital in a dynamic Mirrleesian model incorporating political economy constraints. Policies are chosen sequentially over time, without commitment. Our main result is that the marginal tax on capital income is progressive, in the sense that richer agents face higher marginal tax rates.
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Economies with private information provide a rationale for capital taxation. In this paper we ask what the welfare gains from following this prescription are. We develop a method to answer this question in standard general equilibrium models with idiosyncratic uncertainty and incomplete markets. We find that general equilibrium forces are important and greatly reduce the welfare gains. Once these effects are taken into account, the gains are relatively small in our benchmark calibration. These results do not imply that dynamic aspects of social insurance design are unimportant, but they do suggest that capital taxation may play a modest role.
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This paper analyzes the possibility and the consequences of rational bubbles in a dynamic economy where financially constrained firms demand and supply liquidity. Bubbles are more likely to emerge, the scarcer the supply of outside liquidity and the more limited the pledgeability of corporate income; they crowd investment in (out) when liquidity is abundant (scarce). We analyze extensions with firm heterogeneity and stochastic bubbles.
Download paperWe present a model with altruistic parents and heterogeneous productivity. We derive two key properties for optimal estate taxation. First, the estate tax should be progressive, so that parents leaving a higher bequest face a lower net return on bequests. Second, marginal estate taxes should be negative, so that all parents face a marginal subsidy on bequests. Both properties can be implemented with a simple nonlinear tax on bequests, levied separately from the income tax. These results apply to other intergenerational transfers, such as educational investments, and are robust to endogenous fertility choices. Both estate or inheritance taxes can implement the optimal allocation, but we show that the inheritance tax has some advantages. Finally, when we impose an ad hoc constraint requiring marginal estate taxes to be nonnegative, the optimum features a zero tax up to an exception level, and a progressive tax thereafter.
Download paperThis paper is a normative investigation of the theoretical and quantitative properties of optimal capital taxation in the neoclassical growth model with aggregate shocks and incomplete markets. The model features a representative-agent economy with linear taxes on labor and capital. I first allow the government to trade only a real risk-free bond. Taxes on capital are set one period in advance, reflecting inertia in tax codes and preventing replication of the complete markets allocation. Optimal policy has the following features: labor taxes fluctuate very little; capital taxes are volatile and feature a positive (negative) spike after a negative (positive) shock to the government budget; and capital taxes average to roughly zero across periods. I then consider the implications of allowing the government to trade capital. Optimality calls for a large short position.
Download paperThis paper studies a Diamond-Dybvig model of
financial intermediation providing insurance against unobservable liquidity shocks in the presence of unobservable trades on private markets. We show that in this case competitive equilibria are inefficient. A social planner fi
nds it benefi
cial to introduce a wedge between the interest rate implicit in optimal allocations and the economy's marginal rate of transformation. This improves risk-sharing by reducing the attractiveness of joint deviations where agents simultaneously misrepresent their type and engage in trades on private markets. We propose a simple implementation of the optimum that imposes a constraint on the portfolio share that
financial intermediaries need to invest in short-term assets. In the case of Diamond-Dybvig preferences, the optimal allocation coincides with the unconstrained optimum. For more general preferences, the optimal allocation does not coincide with the unconstrained optimum, and the direction of the policy intervention depends on the nature of the shocks in a manner that we precisely characterize.
Download paperThis paper derives an intertemporal optimality condition for economies with private information, focusing on a class of recursive preferences. By comparing it to the situation where agents can freely save in a risk-free asset market, we derive the optimal savings distortions necessary for constrained optimality. Our recursive preferences are homogeneous and satisfy a balanced-growth condition, while allowing us to separate the role of risk aversion and intertemporal elasticity of substitution. We perform some quantitative exercises that disentangle the respective roles played by these two parameters in optimal distortions and the implied welfare gains.
Download paperThe sustained rise in US current account deficits, the stubborn decline in long-run real rates, and the rise in US assets in global portfolios appear as anomalies from the perspective of conventional models. This paper rationalizes these facts as an equilibrium outcome when different regions of the world differ in their capacity to generate financial assets from real investments. Extensions of the basic model generate exchange rate and foreign direct investment excess returns broadly consistent with the recent trends in these variables. The framework is flexible enough to shed light on a range of scenarios in a global equilibrium environment.
Download paperWe study optimal consumption and portfolio choice in a framework where investors adjust their labor supply through an irreversible choice of their retirement time. We show that investing for early retirement tends to increase savings and reduce an agent’s effective relative risk aversion, thus increasing her stock market exposure. Contrary to common intuition, an investor might find it optimal to increase the proportion of financial wealth held in stocks as she ages and accumulates assets, even when her income and the investment opportunity set are constant. The model predicts a decrease in risk aversion following strong market gains like those observed in the nineties.
Download paperAwarded the Geewax, Terker Prize in Investment Research, Rodney L. White Center for Financial Research, 2005.
We explore steady-state inequality in an intergenerational model with altruistically linked individuals who experience privately observed taste shocks. When the welfare function depends only on the initial generation, efficiency requires immiseration: inequality grows without bound and everyone’s consumption converges to zero.We study other efficient allocations in which the welfare function values future generations directly, placing a positive but vanishing weight on their welfare. The social discount factor is then higher than the private one, and for any such difference we find that consumption exhibits mean reversion and that a steady-state, cross-sectional distribution for consumption and welfare exists, with no one trapped at misery.
We propose a framework for understanding episodes of vigorous economic expansion and extreme asset valuations. We interpret this phenomenon as a high-valuation equilibrium with a low cost of capital based on optimism about future funding. The key ingredient for such equilibrium is feedback from increased growth to a decline in the long-run cost of capital. This feedback arises when an expansion comes with technological progress in the capital sector, when fiscal rules generate procyclical fiscal surpluses, when the rest of the world has lower expansion potential or high saving needs, and when financial constraints are relaxed by the expansion itself.
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