Any credit or refund allowed or made under section
6411 shall be made without regard to the provisions of subsection (a) of this section. In any such case, if the credit or refund, reduced by any deficiency in such tax thereafter assessed and by deficiencies in any other tax resulting from adjustments reflected in the determination of the credit or refund, is in excess of $2,000,000, there shall be submitted to such committee a report containing the matter specified in subsection (a) at such time after the making of the credit or refund as the Secretary shall determine the correct amount of the tax.