Tax harmonization entails a uniform rate that may not suit all governments. Harmonization can advance collective governmental objectives only if the standard deviation of tax rates is less than the average downward effect of tax competition on rates. Since an efficient harmonized tax rate undoes...

We consider an environment in which there is substantial uncertainty about the potential negative external effects of AI algorithms. We find that subjecting algorithm implementation to regulatory approval or mandating testing is insufficient to implement the social optimum. When testing costs...

This paper investigates how tax rates and tax enforcement jointly impact fiscal capacity in low-income countries. We study a policy experiment in the D.R. Congo that randomly assigned 38,028 property owners to the status quo tax rate or to a rate reduction. This variation in tax liabilities...

This paper characterizes the optimal taxation of top earners in a world with externalities. It takes a reduced-form approach that spans a broad class of models where top earners create externalities on the economy. The model allows for a flexible relationship between top earnings and the...

Minimum tax rules constrain only the lowest-tax jurisdictions. Because higher minimum tax rates expand the circle of affected countries and therefore the impact of any further changes, there can be dominated regions over which no parameter values would make a minimum tax efficient. Applying a...

We study the optimal taxation of expenditures that generate income while also serving a consumption function. We characterize the Pareto optimal income tax deduction for such mixed-purpose expenditures within a generalized Atkinson-Stiglitz model. Pareto optimality requires a partial deduction...

This paper studies the welfare effects of unemployment insurance (UI) in low-income countries characterized by high levels of informality, weak enforcement of UI claims, and job search frictions. We assess the impact of UI on workers' welfare in the presence of moral hazard and liquidity...

This paper asserts that reporting of the ratio of welfare gains to tax revenue should be standard protocol in economic analyses of externality correcting taxes. That this comparison might matter is somewhat of a "blind spot" in most economic analyses, for it plays virtually no role when...

We summarize recent methods to study optimal spatial policies. We center the discussion on policies that implement the optimal distribution of population in the presence of spatial spillovers, spatial transfers to optimally tackle redistribution between rich and poor regions, and optimal...

We revisit the rationale for place-based policies using a canonical urban framework with agglomeration spillovers. We derive six main lessons. First, the spatial allocation is inefficient even when spillover elasticities are constant across regions. Second, under constant and positive spillover...