The term controlling United States shareholders means those United States shareholders (as defined in section 951(b)) who, in the aggregate, own (within the meaning of section 958(a)) greater than 50 percent of the total combined voting power of all classes of stock of the foreign corporation entitled to vote. If the foreign corporation is a controlled foreign corporation (as described in section 957) but the United States shareholders do not, in the aggregate, own the requisite voting power, the term "controlling United States shareholders" means all the United States shareholders (as defined in section 951(b)) who own (within the meaning of section 958(a)) stock of the controlled foreign corporation.
For purposes of this paragraph (d)(5), the date in which the electing QBU makes the dollar election shall be the last day of the electing QBU's taxable year. The district director may permit the related party to make such adjustments beginning one taxable year later if, in the district director's sole judgment, reasonable cause exists for the related party not being able to make the required adjustments for the earlier year.
26 C.F.R. §1.985-2