Why are tax revenues of local governments so low?

Using a unique data set on federal grants and tax revenues of more than 5000 Brazilian cities, we find that the federal government imposes an implicit tax of almost 10% on city governments' tax revenues: for every dollar that a city collects from its residents, the federal government withdraws grants worth 9 cents from the city. Our findings suggest that local government tax revenues are low not because federal grants crowd out tax revenues, but because tax revenues crowd out federal grants.