On June 20, 2024, the U.S. Supreme Court affirmed a 2022 decision of the U.S. Court of Appeals for the Ninth Circuit upholding the constitutionality of the mandatory repatriation tax (“MRT”) under section 965 of the U.S. Internal Revenue Code (“the Code”). The MRT requires U.S. taxpayers who own at least 10 percent of a controlled foreign corporation (“CFC”) to pay a one-time tax on their share of the corporation's past earnings and profits, regardless of whether such income was distributed to them. In a 7-2 decision authored by Justice Brett M. Kavanaugh, the Supreme Court held in Moore v. United States1 that Congress can attribute an entity’s realized and undistributed income to its shareholders or partners and then tax them on that income.
Though the holding by the Supreme Court is a significant victory for the government, the most noteworthy part of the holding may be that it does not address a central question posed by the taxpayers in the case: Is the realization of income a constitutional requirement for an income tax?