Which amendment established federal income tax?

• A. 8th Amendment
• B. 20th Amendment
• C. 15th Amendment
• D. 16th Amendment

Answer: (D)

The important point here is which amendment actually gives Congress the power to tax individual incomes without tying those taxes to state populations. The 16th Amendment does exactly that: it authorizes Congress to lay and collect taxes on incomes from any source, without apportionment among the states and without regard to census results. This removed the previous constitutional hurdle and made the federal income tax constitutional and broadly applicable.

Before this amendment, a Supreme Court decision in the 1890s had challenged that approach, creating uncertainty about whether a federal income tax could be legal. Ratified in 1913, the 16th Amendment provided a clear constitutional basis for the modern federal income tax system, which is why it’s the correct choice. The other amendments address different issues—criminal punishment, presidential terms, and voting rights—not the authority to tax incomes.