772.9.1.1. If an amount is deemed under section 603.1 to be a taxable dividend received by a person in a taxation year of the person in respect of a partnership, and it may reasonably be considered that all or part of the amount (in this section referred to as the “foreign-source portion”) is attributable to income of the partnership from a source in a foreign country, the person is deemed for the purposes of this chapter to have income from that source for the year equal to the amount determined by the formula
A × B/C.
In the formula in the first paragraph,(a) A is the amount included under section 497 in computing the person’s income for the year in respect of the taxable dividend;
(b) B is the foreign-source portion; and
(c) C is the amount of the taxable dividend deemed to be received by the person.