38 CFR § 21.9520 - Basic eligibility.
(a) Serves a minimum of 90 aggregate days excluding entry level and skill training (to determine when entry level and skill training may be included in the total creditable length of service, see § 21.9640(a)) and, after completion of such service, -
(1) Continues on active duty;
(2) Is discharged from service with an honorable discharge;
(3) Is released from service characterized as honorable and placed on the retired list, temporary disability retired list, or transferred to the Fleet Reserve or the Fleet Marine Corps Reserve;
(4) Is released from service characterized as honorable for further service in a reserve component; or
(5) Is discharged or released from service for -
(i) A medical condition that preexisted such service and is not determined to be service-connected;
(iii) A physical or mental condition that interfered with the individual's performance of duty but was not characterized as a disability and did not result from the individual's own misconduct;
(b) Serves a minimum of 30 continuous days and, after completion of such service, is discharged under other than dishonorable conditions due to a service-connected disability; or
(1) After meeting the minimum service requirements in paragraph (a) or (b) of this section -
(i) An individual makes an irrevocable election to receive benefits under 38 U.S.C. chapter 33 by relinquishing eligibility under either 38 U.S.C. chapter 30, or 10 U.S.C. chapter 106a, 1606, or 1607;
(ii) A member of the Armed Forces who is eligible for educational assistance under 38 U.S.C. chapter 30 and who is making contributions towards such educational assistance under 38 U.S.C. 3011(b) or 3012(c) makes an irrevocable election to receive benefits under 38 U.S.C. chapter 33; or
(iii) A member of the Armed Forces who made an election not to receive educational assistance under 38 U.S.C. chapter 30 in accordance with 38 U.S.C. 3011(c)(1) or 3012(d)(1) makes an irrevocable election to receive benefits under 38 U.S.C. chapter 33.
(2) An individual may make an irrevocable election to receive benefits under this chapter by properly completing VA Form 22-1990, submitting a transfer-of-entitlement designation under this chapter to the Department of Defense, or submitting a written statement that includes the following -
(i) Identification information (including name, social security number, and address);
(ii) If applicable, an election to receive benefits under chapter 33 in lieu of benefits under one of the applicable chapters listed in paragraph (c)(1)(i) of this section (e.g., “I elect to receive benefits under the Post-9/11-GI Bill in lieu of benefits under the Montgomery GI Bill - Active Duty (chapter 30) program.”);
(iii) The date the individual wants the election to be effective (e.g., “I want this election to take effect on August 1, 2009.”). An election request for an effective date prior to August 1, 2009, will automatically be effective August 1, 2009; and
(iv) An acknowledgement that the election is irrevocable (e.g., “I understand that my election is irrevocable and may not be changed.”).