For purposes of section
951
(a), the earnings and profits of a controlled foreign corporation attributable to amounts which are, or have been, included in the gross income of a United States shareholder under section
951
(a), shall not, when distributed through a chain of ownership described under section
958
(a), be also included in the gross income of another controlled foreign corporation in such chain for purposes of the application of section
951
(a) to such other controlled foreign corporation with respect to such United States shareholder (or to any other United States shareholder who acquires from any person any portion of the interest of such United States shareholder in the controlled foreign corporation, but only to the extent of such portion, and subject to such proof of identity of such interest as the Secretary may prescribe by regulations).