399. The amounts required to be deducted in computing the cumulative Canadian exploration expenses of a taxpayer at the time referred to in section 398 are the aggregate of:(a) all amounts deducted, or required to be deducted, in computing his income for a taxation year ending before that time in respect of such expenses;
(b) all amounts that become receivable by him before that time that are required to be deducted in computing such expenses under this paragraph by virtue of section 386 or 391;
(c) all amounts paid to him after 6 May 1974 in the case of an oil business, or after 31 March 1975 in the case of a mining business, and before 25 May 1976 as a subsidy, grant or assistance received under an Act, in respect of Canadian exploration and development expenses or Canadian exploration expenses, to the extent provided by the regulations;
(d) all amounts received by the taxpayer before such time in respect of a debt referred to in paragraph d of section 398;
(e) all amounts of assistance that he has received or is entitled to receive in respect of any Canadian exploration expense incurred after 31 December 1980 or that can reasonably be related to Canadian exploration activities after that date, to the extent that the assistance has not reduced his Canadian exploration expense by virtue of the third paragraph of section 399.3;
(e.1) all amounts by which his cumulative Canadian exploration expense is required, because of section 485.8, to be reduced at or before that time;
(f) all amounts that are required to be deducted before that time under section 392.2 in computing his cumulative Canadian exploration expenses;
(g) that portion of the aggregate of all amounts each of which is an amount deducted by the taxpayer under subsection 5 or 6 of section 127 of the Income Tax Act (Revised Statutes of Canada, 1985, chapter 1, 5th Supplement) for a taxation year ending before that time that may reasonably be attributed to an expenditure made in a preceding taxation year that is a qualified Canadian exploration expenditure, within the meaning of subsection 9 of section 127 of that Act, as it read for that preceding taxation year, or a pre-production mining expenditure, within the meaning of that subsection 9; and
(h) all amounts that are required to be deducted before that time under paragraph b of section 418.31 in computing his cumulative Canadian exploration expenses.