26 CFR § 601.104 Collection functions. (a) Collection methods (2) Withholding of tax at source. Withholding at the source of income payments is an important method used in collecting taxes. For example, in the case of wage earners, the income tax is collected in large part through the withholding by employers of taxes on wages paid to their employees. The tax withheld at the source on wages is applied as a credit in payment of the individual's income tax liability for the taxable year. In no case does withholding of the tax relieve an individual from the duty of filing a return otherwise required by law. The chief means of collecting the income tax due from nonresident alien individuals and foreign corporations having United States source gross income which is not effectively connected with the conduct of a trade or business in the United States is the withholding of the tax by the persons paying or remitting the income to the recipients. The tax withheld is allowed as a credit in payment of the tax imposed on such nonresident alien individuals and foreign corporations.
