38 C.F.R. § 21.5052
(a) Minimum period of participation. Each individual who agrees to participate must do so for a minimum period of 12 consecutive months, unless the participant:
(5) Elects to make a lump-sum contribution which, when taken together with his or her other contributions, equals the equivalent of at least 12 months' participation.
(Authority: 38 U.S.C. 3221, 3222)
(b) Amount of monthly contribution. The individual shall specify the amount of his or her contribution to the fund.
(e) Prohibition against contributing. An individual may not make contributions to the fund after the date of his or her discharge. The VA does not consider the return of an unnegotiated refund check to be a contribution. A person who returns a refund check remains continuously eligible for benefits.
(Authority: 38 U.S.C. 3222)
(f) Lump-sum contribution. After September 30, 1980 an individual may make a lump-sum contribution or contributions in place of or in addition to monthly contributions.
(1) A lump-sum contribution:
(2) The Department of Veterans Affairs will consider the lump-sum contributions to have been made by monthly deductions from the participant's military pay at the rate of $100 per month unless the participant specifies a different rate which must be
(3) If otherwise eligible to make contributions, a participant:
(i) May make a lump-sum contribution to cover any period of his or her active duty. This may entail a retroactive period, including one which—
(B) Although made after October 27, 1986, includes all or part of the period beginning on July 1, 1985, and ending on October 27, 1986.
(Authority: Pub. L. 99-576, sec. 309(c))
(4) A participant may make as many lump-sum contributions as he or she desires, but he or she may not make more than one lump-sum contribution per month.
(Authority: 38 U.S.C. 3222(d)
[45 FR 31, Jan. 2, 1980, as amended at 47 FR 51744, Nov. 17, 1982; 48 FR 50530, Nov. 2, 1983; 53 FR 617, Jan. 11, 1988; 53 FR 34496, Sept. 7, 1988]