United States. Library of Congress. "A Century of Lawmaking for a New Nation: U.S. Congressional Documents and Debates 1774-1873." American Memory. http://memory.loc.gov/ammem/amlaw/lawhome.html
American Memory is a project of the Library of Congress to digitize many kinds of historical documents from their collection. One of the collections is " A Century of Lawmaking for a New Nation: U.S. Congressional Documents and Debates 1774-1873." The House and Senate Journals as well as the Annals of Congress and the Journals of the Continental Congress are available in this collection, as are the Statutes at Large, a chronological arrangement of laws passed by Congress, and several accounts of the Continental Congress and early congresses by individuals. These documents can be searched separately or as a group from the "Search All Law Titles" screen, or click on the individual titles to retrieve a specific document or to browse. Also, make sure to visit the main page for the American Memory project, which is linked from this collection and contains many interesting historical documents.
At the "Search All Titles" screen, enter "income tax" without the quotes in the large text box and choose "match this exact phrase" in the box just under the text box. You will see an image of what was being said on the subject of income taxation in 1814, almost 100 years before the imposition of the income tax we are so familiar with today.