(a) To meet the gross income requirement, it is necessary that either of the following percentages of gross income of the corporation for the taxable year (including the additions to gross income provided in section 555(b) as required by section 555(c)(2)) be foreign personal holding company income as defined in section 553:
(1) 60 percent or more; or
(2) 50 percent or more if the foreign corporation has been classified as a foreign personal holding company for any taxable year ending after August 26, 1937, unless:
(i) A taxable year has intervened since the last taxable year for which it was so classified, during no part of which the stock ownership requirement specified in section 552(a)(2) exists; or
(ii) Three consecutive years have intervened since the last taxable year for which it was so classified, during each of which its foreign personal holding company income was less than 50 percent of its gross income.
(b) In determining whether the foreign personal holding company income is equal to the required percentage of the total gross income, the determination must not be made upon the basis of gross receipts, since gross income is not synonymous with gross receipts. For meaning of gross income in this part, see section 555 and Sec. 1.555-1.