How States could not use poll taxes to deny a person the right to vote according to which amendment?

States cannot use poll taxes to deny a person the right to vote according to the 24th Amendment to the United States Constitution, ratified in 1964. This amendment prohibits the imposition of any tax in federal elections, and it was later affirmed by the Supreme Court in the case of Harper v. Virginia Board of Elections (1966), which extended this prohibition to state elections as well. Poll taxes were deemed a discriminatory practice that disproportionately affected low-income individuals and minorities.