336.0.4. A taxpayer may, in computing the income of the taxpayer for a taxation year, deduct the amount by which an amount paid by the taxpayer in the year or one of the two preceding taxation years under an order of a competent tribunal as a repayment of an amount included under any of paragraphs a to b.1 of section 312, as it read for a preceding taxation year, in computing the taxpayer’s income for that preceding year, or that should have been so included had the taxpayer not made the election provided for in section 309.1, as it read for that preceding year, or included under section 312.4 in computing the taxpayer’s income for the year or a preceding taxation year, to the extent that the amount was not deducted in computing the taxpayer’s income for a preceding taxation year, exceeded the portion of the amount in respect of which section 334.1 applied for a preceding taxation year, as that section read for that preceding year.