Any portion of a refund made under section
6416
(a)(4) and any portion of a payment made under section
6420,
6421, or
6427 which constitutes an excessive amount (as defined in section
6675
(b)), and any civil penalty provided by section
6675, may be assessed and collected as if it were a tax imposed by section
4081 (with respect to refunds under section
6416
(a)(4) and payments under sections
6420 and
6421), or 4041 or 4081 (with respect to payments under section
6427) and as if the person who made the claim were liable for such tax. The period for assessing any such portion, and for assessing any such penalty, shall be 3 years from the last day prescribed for the filing of the claim under section
6416
(a)(4),
6420,
6421, or
6427, as the case may be.