If the allowance of a credit or refund of an overpayment of tax attributable to a credit carryback is otherwise prevented by the operation of any law or rule of law other than section
7122, relating to compromises, such credit or refund may be allowed or made, if claim therefor is filed within the period provided in subparagraph (A) of this paragraph. In the case of any such claim for credit or refund, the determination by any court, including the Tax Court, in any proceeding in which the decision of the court has become final, shall not be conclusive with respect to any credit, and the effect of such credit, to the extent that such credit is affected by a credit carryback which was not in issue in such proceeding.