Which amendment established a tax on income?

The Sixteenth Amendment to the United States Constitution established the federal government's authority to impose a tax on income. Ratified in 1913, this amendment allows Congress to levy taxes on individuals' income without apportioning it among the states or basing it on the United States Census. This was a significant shift in the way the federal government could generate revenue, enabling a more stable and predictable source of funding for government operations.

The other amendments listed do not pertain to income taxation. The Seventeenth Amendment addresses the direct election of senators, the Eighteenth Amendment dealt with the prohibition of alcohol, and the Twenty-second Amendment limits the number of terms a president can serve. These distinctions highlight the unique purpose and historical context of the Sixteenth Amendment in relation to federal tax policy.