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 poll tax or other tax.
The Congress shall have power to enforce this article by appropriate legislation.
The twenty-fourth amendment prohibits a poll tax to be in place on any federal election.
Here is an overview on what a poll tax is all about.
Here is a video of a riot that broke out due to the usage of a poll tax.