674.5. Where a person remits tax under section 628 or 640 calculated on the consideration or a part thereof for a taxable supply and that consideration or part thereof is subsequently reduced, to the extent that the person did not claim, and is not, but for this section, entitled to claim, an input tax refund or a rebate in respect of the portion of the tax that was calculated on the amount by which the consideration or part thereof was reduced, that portion is deemed, for the purpose of determining a rebate under sections 400 to 402.2, to be an amount that was not payable or remittable by the person.
This section does not apply in circumstances in which section 57 or sections 213 to 219 apply.