(a) A member who is entitled to educational assistance under this chapter and who reenlists at the end of the enlistment which established such entitlement may, at the time of such reenlistment, elect to receive a lump-sum payment computed under subsection (b) in lieu of receiving such educational assistance. An election to receive such a lump-sum payment is irrevocable.

(b) The amount of a lump-sum payment under subsection (a) is 60 percent of the sum of—

(1) the product of (A) the rate for educational assistance under section 2143(b) of this title applicable to such member which is in effect at the time of such reenlistment, and (B) the number of standard academic years of entitlement of such member to such assistance; and

(2) the product of (A) the rate for the subsistence allowance authorized under section 2144 of this title for pursuit of a course of instruction on a full-time basis at the time of such reenlistment, and (B) the number of months of entitlement of such member to such allowance.