(a) In general. An agreement entered into as provided in § 36.3121(l) (1)-1 shall be in effect for the period beginning with the first day of the calendar quarter in which the agreement is signed by the district director or director of the service center, or the first day of the calendar quarter following the calendar quarter in which the agreement is signed by the district director or director of the service center, whichever is specified in the agreement. In no case, however, shall the agreement be effective for any calendar quarter which begins prior to January 1, 1955.

(b) Amendment of agreement. If an amendment on Form 2032 Supplement (filed by a domestic corporation to include in its agreement services performed for a foreign subsidiary not previously named therein) is signed by the district director or director of the service center, within the quarter for which the agreement is first effective or within the first calendar month following such quarter, the agreement shall be effective with respect to the subsidiary named in the amendment as of the date such agreement first became effective. However, if the amendment is signed by the district director or director of the service center after the last day of the fourth month for which the agreement is in effect, such agreement shall be in effect with respect to the subsidiary named in the amendment for the period beginning with the first day of the calendar quarter following the calendar quarter in which the amendment is signed by the district director or director of the service center.