The standard Principal–Agent (PA) model assumes that the principal can control the agent's consumption profile. In an intertemporal setting, however, Rogerson (1985, Econometrica53, 69–76) shows that given the optimal PA contract, the agent has an unmet precautionary demand for savings. Thus the standard PA model is invalid if the agent has access to credit markets. In this paper we generalize the standard PA model to allow for saving and borrowing by the agent. We show that the impact of such access critically depends upon the treatment of default. If default is not permitted, efficiency is strictly reduced by the introduction of credit markets, and the equilibrium level of borrowing or saving is indeterminate in the model. If default is allowed, however, the optimal contract depends upon the level of bankruptcy protection in the economy, which is described by a minimum level of wage income. We show that there is an optimal intermediate range of bankruptcy protection. Within this range, allowing default increases efficiency in the economy relative to the case of no default. Also, the model predicts specific levels of consumer debt, interest rates, and default rates as functions of the level of bankruptcy protection level. Journal of Economic Literature Classification Numbers: D80, G21, G28, J30.

We study environments in which agents may borrow sequentially from more than one lender. Although debt is prioritized, additional lending imposes an externality on prior debt because, with moral hazard, the probability of repayment of prior loans decreases. Equilibrium interest rates are higher than they would be if borrowers could commit to borrow from at most one bank. Even though the loan terms are less favorable than they would be under commitment, the indebtedness of borrowers is greater. Further, additional lending causes the probability of default to increase. The results apply to markets for consumer, corporate, and international debt.

We study environments in which agents may borrow sequentially from more than one lender. Although debt is prioritized, additional lending imposes an externality on prior debt because, with moral hazard, the probability of repayment of prior loans decreases. Equilibrium interest rates are higher than they would be if borrowers could commit to borrow from at most one bank. Even though the loan terms are less favorable than they would be under commitment, the indebtedness of borrowers is greater. Further, additional lending causes the probability of default to increase. The results apply to markets for consumer, corporate, and international debt.

Recent debate has focused on the desirability of imposing an oil import fee or some broader tax on oil consumption in order to finance tax reform or for some other purposes. Optimal taxation requires that the government raise revenue using the tax instrument with the lowest efficiency cost per dollar of additional revenue. A highly stylized but conventional general-equilibrium model is used to evaluate the magnitude of this marginal efficiency cost for taxes on oil imports, oil consumption, and, as a reference for comparison, labor income.

While taxes may be certain, U.S. tax policy has certainly not been. Furthermore, intrinsic economic risk makes investment decisions risky. Therefore, a serious examination of the effects of tax policy on dynamic economic behavior should consider both sources of uncertainty. This paper presents a simple theoretical and computational model that can analyze both intrinsic risk and uncertain taxation. Furthermore, it will be clear that these techniques will be useful for examining general problems of taxation and risk. When studying the impact of past and/or proposed tax changes, one of two extreme assumptions are usually made: either agents are perfectly aware of future tax policy, a perfect foresight assumption, or they always believe that no change will ever occur, a myopic foresight assumption. These two assumptions yield substantially different views of recent tax experience, as Alan Auerbach and James Hines (1987) demonstrate in a partial-equilibrium context. Both are clearly wrong. The myopic specification assumes that individuals believe at each point in time that the current tax law will surely continue forever, even after they have been hit repeatedly with tax changes. On the other hand, it is absurd to think that in, say, 1977, a significant number of individuals perfectly knew the various tax changes that would occur during the following decade. This paper analyzes a dynamic general equilibrium model wherein taxpayers understand the uncertainty in tax policy when making their deci-