Permits Congress to levy an income tax without apportioning it among the various states or basing it on the United States Census. Proposed July 12, 1909; ratified February 3, 1913, 3 years and 6 months later. The Sixteenth Amendment to the United States Constitution allows Congress to levy an income tax without apportioning it among the states on the basis of population. It was passed by Congress in 1909 in response to the 1895 Supreme Court case of Pollock v. Farmers' Loan & Trust Co. The Sixteenth Amendment was ratified by the requisite number of states on February 3, 1913, and effectively overruled the Supreme Court's ruling in Pollock. Wiki link