In this paper, we derive principles of optimal cyclical monetary policy in an economy without capital, with a cash-in-advance restriction on household transactions, and monopolistic firms that set prices one period in advance. The only distortionary policy instruments are the nominal interest rate and the money supply. In this environment it is feasible to undo both the cash-in-advance and price setting restrictions, but not the distortion due to monopolistic competition. We show that it is optimal to follow the Friedman rule, and thus offset the cash-in-advance restriction. We also find that, in general, it is not optimal to undo the price setting restriction, so that a simple criterion of eliminating gaps is not optimal. Sticky prices provide the planner with tools to improve upon a distorted flexible price allocation.

Using a quantitative model that features technical progress in automation and endogenous skill choice, we show that, given the current U.S. tax system, a sustained fall in automation costs can lead to a massive rise in income inequality. We characterize the optimal tax system in this model. We find that it is optimal to tax robots while the current generations of routine workers, who can no longer move to non-routine occupations, are active in the labour force. Once these workers retire, optimal robot taxes are zero.

In this article, we analyze the implications of price‐setting restrictions for the conduct of cyclical fiscal and monetary policy. We consider standard monetary economies that differ in the price‐setting restrictions imposed on the firms. We show that, independently of the degree or type of price stickiness, it is possible to implement the same efficient set of allocations and that each allocation in that set is implemented with policies that are also independent of the price stickiness. In this sense, environments with different price‐setting restrictions are equivalent.

How should countries cooperate in setting fiscal and trade policies when government expenditures must be financed with distorting taxes? We show that even if countries cannot make explicit transfers to each other, every point on the Pareto frontier is production efficient, so that international trade and capital flows should be effectively free. Trade agreements must be supplemented with fiscal policy agreements. Residence-based income tax systems have advantages over source-based systems. Taxing all household asset income at a country-specific uniform rate and setting the corporate income tax to zero yield efficient outcomes. Value-added taxes should be adjusted at the border.

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.