Which amendment established the federal income tax?

• A. The Sixteenth Amendment
• B. The Thirteenth Amendment
• C. The Nineteenth Amendment
• D. The Twenty-First Amendment

Answer: (A)

The central idea here is who has the power to tax income and how that power is defined in the Constitution. The Sixteenth Amendment explicitly grants Congress the authority to lay and collect taxes on incomes, from whatever source derived, without apportionment among the states and without regard to any census. Ratified in 1913, this amendment removed the earlier constitutional hurdle that treated income taxes as unconstitutional unless they were apportioned by state population. By declaring that income taxes can be levied directly and without apportionment, it provides a straightforward and unambiguous basis for the federal income tax.

The other amendments address completely different issues: the Thirteenth abolishes slavery, the Nineteenth guarantees women the right to vote, and the Twenty-First repeals Prohibition. None of these change the federal government’s power to tax income, so they don’t fit as the source of the federal income tax authority.