The Sixteenth Amendment took effect on February 25, 1913, followed by the Revenue Act of 1913 (Public Law 63-16) and the 1913 Form 1040. For information about early U.S. tax legislation, see: Guide and Analytical Index to the Internal Revenue Acts of the United States, 1909 – 1950 by Bernard D. Reams (in microform) and Taxation and Economic Reform in America, Parts I & II, 1781 – (on Hein Online), which includes the Reams title. Also see the Library of Congress’s History of the US Income Tax and Tax Analysts’ Tax History Museum for additional documents and explanation.