Abstract
This paper builds a new microdatabase that covers 100 countries at all income levels and long-run time series in the United States (1870–2010) and Mexico ( 1960–2010) to document how the modern tax system arises over development. I establish a new set of stylized facts, which show that the income tax exemption threshold decreases in the income distribution as a country develops, tracking growth in the employee share of employment that occurs gradually further down the income distribution. Additional evidence supports the interpretation that the rise in third-party covered income through increases in employee share drives expansions of the income tax base over development. (JEL D31, H23, H24, H71, J22, J23, N40)