(a) the amount by which the aggregate of all amounts by which the amount determined under this paragraph in respect of the taxpayer is required, because of section 485.8, to be reduced at or before the end of the year is exceeded by the aggregate of the foreign exploration and development expenses, to the extent that they were not deductible in computing the taxpayer’s income for a previous taxation year, incurred by the taxpayer i. before the end of the year,
ii. at a time at which the taxpayer was resident in Canada, and
iii. where the taxpayer became resident in Canada before the end of the year, after the last time, before the end of the year, that the taxpayer became resident in Canada; and