157.6. Where a taxpayer disposes of a property that is a right in a debt obligation for consideration equal to its fair market value at the time of disposition, there may be deducted in computing the taxpayer’s income for the taxation year in which the disposition occurs the amount by which the aggregate of all amounts each of which was included in computing the taxpayer’s income for the year or a preceding taxation year as interest on the property exceeds the aggregate of all amounts each of which is(a) such portion of an amount that was received or became receivable by him in the year or in a preceding taxation year as can reasonably be considered to be in respect of an amount that was included in computing his income for the year or a preceding taxation year as interest on the property and that was not repaid by the taxpayer to the issuer of the debt obligation because of an adjustment in respect of interest received before the time of disposition by the taxpayer, or
(b) an amount in respect of the property that was deductible by him by virtue of the second paragraph of section 167 in computing his income for the year or a preceding taxation year.