Optimal Spatial Taxation: Are Big Cities too Small?

We analyze the role of optimal income taxation across different local labor markets. Should labor in large cities be taxed differently than in small cities? We find that a planner who needs to raise a given level of revenue and is constrained by free mobility of labor across cities does not choose equal taxes for cities of different sizes. The optimal tax schedule is location specific and tax differences between large and small cities depends on the level of government spending, the concentration of housing wealth and the strength of agglomeration economies. Our estimates for the US imply higher optimal marginal rates in big cities than in small cities. Under the current Federal Income tax code with progressive taxes, marginal rates are already higher in big cities which have higher wages, but the optimal difference we estimate is lower than what is currently observed. Simulating the US economy under the optimal tax schedule, there are large effects on population mobility: the fraction of population in the 5 largest cities grows by 7.6% with 3.4% of the country-wide population moving to bigger cities. The welfare gains however are smaller. This is due to the fact that much of the output gains are spent on the increased costs of housing construction in bigger cities. Aggregate goods consumption goes up by 1.51% while aggregate housing consumption goes down by 1.70%.