Any portion of an internal revenue tax (or any interest, assessable penalty, additional amount, or addition to tax) which has been erroneously refunded, and which is recoverable by a civil action pursuant to 26 U.S.C. 7405,shall.93 of this part.
(26 U.S.C. 6602)
[T.D. ATF-301, 55 FR 47614, Nov. 14, 1990]