Twenty-fourth Amendment to the United States Constitution
The Twenty-fourth Amendment (Amendment XXIV) of the United States Constitution prohibits both Congress and the states from requiring the payment of a poll tax or any other tax to vote in federal elections. The amendment was proposed by Congress to the states on August 27, 1962, and was ratified by the states on January 23, 1964.
Source: Wikipedia — Twenty-fourth Amendment to the United States Constitution (CC BY-SA 4.0)