657.1.1. No deduction may be made under paragraph a of section 657 in computing the income for a taxation year of a trust in respect of such part of an amount that would otherwise be its income for the year as became payable in the year to a beneficiary who was, at any time in the year, a designated beneficiary of the trust as that expression applies for the purposes of section 210.3 of the Income Tax Act (Revised Statutes of Canada, 1985, chapter 1, 5th Supplement) unless, throughout the year, the trust was resident in Canada.