Since the federal income tax was significantly expanded in 1940, several dozen major tax bills have been enacted. Inevitably, discussions (and disagreements) have arisen concerning the relative size of the bills effects on federal revenues.This paper uses revenue estimates from Treasury and the Joint Committee on Taxation to compare the relative size of the revenue effect of the major tax bills enacted after 1939 using four different measures. An appendix provides a short list of the major provisions in the bills.