When the 24th Amendment was ratified in 1964, five states still retained a poll tax: Alabama, Arkansas, Mississippi, Texas and Virginia. The amendment prohibited requiring a poll tax for voters in federal elections. But it was not until 1966 that the U.S. Supreme Court ruled 6–3 in Harper v. Virginia Board of Elections that poll taxes for any level of elections were unconstitutional. It said these violated the Equal Protection Clause of the Fourteenth Amendment. Subsequent litigation related to potential discriminatory effects of voter registration requirements has generally been based on application of this clause.
Section 1. The right of citizens of the United States to vote in any primary or other election for President or Vice President, for electors for President or Vice President, or for Senator or Representative in Congress, shall not be denied or abridged by the United States or any State by reason of failure to pay any poll tax or other tax.
Section 2. The Congress shall have power to enforce this article by appropriate legislation.