38 CFR § 21.5838 - Overpayments.
(a) Educational assistance. If an individual receives educational assistance but the educational assistance must be discontinued according to § 21.5835, the amount of educational assistance attributable to the portion of the term, quarter or semester following the effective date of discontinuance shall constitute a debt due the United States.
(1) The amount of the debt is equal to the product of—
(i) The number of days the individual was entitled to receive subsistence allowance during the enrollment period for which educational assistance was paid, divided by the total number of days in that enrollment period, and
(ii) The amount of educational assistance provided for that enrollment period.
(2) Nothing in this method of calculation shall change the fact that the number of months of educational assistance to which the individual remains entitled shall always be the same as the number of months of subsistence allowance to which the individual is entitled.
(b) Subsistence allowance. If an individual receives subsistence allowance under any of the following conditions, the amount of that subsistence allowance shall constitute a debt due the United States unless the debt is waived as provided by §§ 1.955 through 1.970 of this chapter.
(1) Subsistence allowance received for courses pursued while on active duty;
(2) Subsistence allowance received for courses which are precluded under § 21.5800(b);
(3) Subsistence allowance received by a person who is not eligible for educational assistance under § 21.5740;
(4) Subsistence allowance received by an individual who has exhausted all entitlement provided under § 21.5742;
(5) Subsistence allowance received by an individual for a period before the commencing date determined by § 21.5831.
(6) Subsistence allowance received by an individual for a period following a discontinuance date determined by § 21.5835.
(7) Subsistence allowance received by an individual in excess of the part-time rate for a period following a reduction date determined by § 21.5835.