Final answer:
The Sixteenth Amendment authorized the federal government to collect personal income taxes, ratified in 1913 to grant Congress the ability to impose a federal income tax without apportionment among the states.
Step-by-step explanation:
The constitutional amendment that authorized the federal government to collect personal income taxes is the Sixteenth Amendment. This amendment was necessary after the Supreme Court deemed previous federal income tax laws unconstitutional. Ratified in 1913, the Sixteenth Amendment states, 'The Congress shall have the power to lay and collect taxes on incomes, from whatever source derived, without apportionment among the several States, and without regard to any census or enumeration.'
Previously, income tax had been implemented during the Civil War to support military expenditures. However, its constitutionality was often questioned. To solidify this source of revenue, the 16th Amendment authorized Congress to impose a federal income tax without distributing it among the states based on population. The implementation of the amendment was influenced by the need to replace tariff revenues and the push for progressive taxation, which taxed individuals based on their income levels.