1121.9. Where a particular trust is a beneficiary under another trust a taxation year of which, in this section referred to as the "other year", ends in a calendar year after 15 December of the year and a particular taxation year of the particular trust ends on 15 December of the year because of section 1121.7, each amount otherwise determined or designated under section 663, 666, 668, 669.3 or 671 for the other year that would otherwise be included, or taken into account, in computing the income of the particular trust for a taxation year subsequent to that year shall be included, or taken into account, in computing the particular trust’s income for the particular year and not be included, or taken into account, in computing the particular trust’s income for the subsequent year.