Methodological Notes for “Income Taxes and Redistribution in the Early Twentieth Century” and “Income Tax Progressivity and Inflation during the World Wars”

This document presents the methodological approach used in two papers about historical income taxes: “Income taxes and redistribution in the early twentieth century” (Torregrosa-Hetland and Sabaté, 2021) and “Income tax progressivity and inflation during the World Wars” (Torregrosa-Hetland and Sabaté, 2019). We first describe the general method and sources used to obtain synthetic distributions of income and calculate the effective income tax rates and the corresponding indices of progressivity and redistribution. Secondly, we discuss the most important country-specific issues that have been taken into account in our calculations. Finally, the third section looks at the accuracy of our synthetic income distributions and tax simulations by comparing them with the original series from the tax statistics. The two aforementioned papers summarize this same information in their methodological sections, but this note goes more in depth into some details that might be of interest to some readers.