34 C.F.R. § 81.31
A recipient that made an unallowable expenditure or otherwise failed to discharge its obligation to account properly for funds shall return an amount that—
(c) Excludes any amount expended in a manner not authorized by law more than five years before the recipient received the notice of a disallowance decision under § 81.34.
(Authority: 20 U.S.C. 1221e-3, 1234(f)(1), 1234a(k), 1234b (a) and (b), and 3474(a))
[54 FR 19512, May 5, 1989; 54 FR 21622, May 19, 1989. Redesignated and amended at 58 FR 43473, Aug. 16, 1993]