27 C.F.R. § 70.265
(a) A refund of any portion of any internal revenue tax (or any interest, additional amount, addition to the tax, or assessable penalty) shall be considered erroneous and a credit of any such portion shall be considered void:
(b) For procedure by the United States to recover erroneous refunds, see sections 6532(b) and 7405 of the Internal Revenue Code.
(26 U.S.C. 6514)
[T.D. ATF-251, 52 FR 19314, May 22, 1987. Redesignated by T.D. ATF-301, 55 FR 47606, Nov. 14, 1990]