Answer :

Reserve Clause (elastic clause)

AKA: The Necessary and Proper Clause (10th Amendment) of the Constitution:

"The Congress shall have Power ... To make all Laws which shall be necessary and proper for carrying into Execution the foregoing Powers, and all other Powers vested by this Constitution in the Government of the United States, or in any Department or Officer thereof."

Answer:

“The Congress shall have power to lay and collect taxes on incomes, from whatever source derived.”

Explanation:

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