26 CFR 509.102 - Applicable provisions of law.
(a) General. The Internal Revenue Code of 1954 provides in part as follows:
Sec. 894. Income exempt under treaty. Income of any kind, to the extent required by any treaty obligation of the United States, shall not be included in gross income and shall be exempt from taxation under this subtitle.
Sec. 7805. Rules and regulations - (a) Authorization. Except where such authority is expressly given by this title to any person other than an officer or employee of the Treasury Department, the Secretary or his delegate shall prescribe all needful rules and regulations for the enforcement of this title, including all rules and regulations as may be necessary by reason of any alteration of law in relation to internal revenue.
(b) Retroactivity of regulations or rulings. The Secretary or his delegate may prescribe the extent, if any, to which any ruling or regulation, relating to the internal revenue laws, shall be applied without retroactive effect.
(b) Internal Revenue Code of 1939. Any reference in §§ 509.101 to 509.122 to any provision of the Internal Revenue Code of 1954 shall, where applicable, be deemed also to refer to the corresponding provision of the Internal Revenue Code of 1939.
(c) Effective date of regulations. Pursuant to sections 894 and 7805 of the Internal Revenue Code of 1954, Article XIX of the convention, and other provisions of the internal revenue laws, §§ 509.101 to 509.122 are hereby prescribed effective for taxable years beginning on or after January 1, 1951. All regulations inconsistent herewith are modified accordingly.