21.4.29. If a taxpayer has, in a reversionary year of the taxpayer, made a particular payment on account of the principal amount of a pre-reversion debt of the taxpayer, the following rules apply:(a) if the taxpayer would have made a gain—or, if the pre-reversion debt was not on account of capital, would have had income—(in the second paragraph referred to as the “hypothetical gain or income”) attributable to a fluctuation in the value of a currency if the pre-reversion debt had been settled by the taxpayer’s having paid, immediately before the end of the taxpayer’s last functional currency year, an amount equal to the principal amount (expressed in the currency in which the pre-reversion debt is denominated, which currency is in this section referred to as the “debt currency”) at that time, the taxpayer is deemed to make a gain or to have income, as the case may be, for the reversionary year equal to the amount determined by the formula
A × B/C; and
(b) if the taxpayer would have sustained a loss—or, if the pre-reversion debt was not on account of capital, would have had a loss—(in this subparagraph referred to as the “hypothetical loss”) attributable to a fluctuation in the value of a currency if the pre-reversion debt had been settled by the taxpayer’s having paid, immediately before the end of the taxpayer’s last functional currency year, an amount equal to the principal amount (expressed in the debt currency) at that time, the taxpayer is deemed to sustain or to have a loss in respect of the particular payment for the reversionary year equal to the amount that would be determined by the formula in subparagraph a if the reference to “hypothetical gain or income” in subparagraph a of the second paragraph were read as a reference to “hypothetical loss”.
In the formula in subparagraph a of the first paragraph,(a) A is the amount of the hypothetical gain or income converted to Canadian currency using the relevant spot rate for the last day of the taxpayer’s last functional currency year;
(b) B is the amount of the particular payment (expressed in the debt currency); and
(c) C is the principal amount of the pre-reversion debt at the beginning of the taxpayer’s first reversionary year (expressed in the debt currency).