Section 3(b) of the Act of April 14, 1966, provides that the amendment made by section 3(a) thereof shall also apply to taxable years of a corporation beginning after December 31, 1962, and ending before April 15, 1966, if the corporation elects to have the amendment apply to such years, and all persons (or their personal representatives) who were shareholders of such corporation at any time during any of such years consent to such election and the application of the amendment. This section prescribes the time for, and manner of, making such election and consents, and also extends the time within which certain new shareholders may consent to an election under section 1372(a) of the Code.
If an election by a corporation under section 1372(a) of the Code is not treated as terminated for a taxable year of the corporation as a result of an election and consents under this paragraph, such election under section 1372(a) of the Code shall be treated as being in effect with respect to all subsequent taxable years of the corporation unless it is otherwise terminated or revoked for any such subsequent year pursuant to section 1372(e) of the Code.
26 C.F.R. §301.9100-19T