38 C.F.R. § 21.4504
(a) General. The agreement by VA to loan money pursuant to 38 U.S.C. 3512(f) and 3698 to any eligible spouse or surviving spouse shall be in the form of a promissory note which shall include:
(3) A note or other written obligation providing for repayment of the principal amount, and interest on the loan in annual installments over a period beginning 9 months after the date on which the borrower first ceases to be at least a half-time student and ending:
(b) Interest. The promissory note shall advise the student that the loan shall bear interest on the unpaid balance of the loan at a rate comparable to, but not in excess of, the rate of interest charged students at such time on loans insured by the Secretary of Education, Department of Education, under part B of Title IV of the Higher Education Act of 1965. The rate shall be determined as of the date the agreement is executed and shall be a fixed amount.
(Authority: 38 U.S.C. 3698)
(d) Default. Whenever VA determines that a default, in whole or in part, has occurred on any such loan the eligible spouse or surviving spouse shall be notified that the amount of the default shall be recovered from the eligible spouse or surviving spouse concerned in the same manner as other debt due the United States. Once a default has occurred, the eligible spouse's or surviving spouse's subsequent reentrance into training at the half-time or greater rate shall not be the basis for rescinding the default. A default may only be rescinded when VA has been led to create the default as a result of a mistake of fact or law.
(Authority: 38 U.S.C. 3698 (e)(1))
[40 FR 31765, July 29, 1975, as amended at 48 FR 37997, Aug. 22, 1983; 52 FR 5963, Feb. 27, 1987; 52 FR 7276, Mar. 10, 1987; 61 FR 26116, May 24, 1996]