(a) An individual who has at least 10 years of service credit, as determined by the board of trustees, for which the individual was eligible to participate in the group benefits program under § 1551.101 or who has at least five years of membership and five years of military service credited in the Employees Retirement System of Texas and who retires in a manner described by this section is eligible, subject to § 1551.1055, to participate as an annuitant in the group benefits program.
(b) An individual is eligible to participate in the group benefits program as provided by Subsection (a) if:
(1) the individual retires under the jurisdiction of the Employees Retirement System of Texas; and
(2) the individual:
(A) receives or is eligible to receive an annuity under § 814.104(a)(2), Government Code, and has at least 10 years of eligible service credit;
(B) receives or is eligible to receive an annuity under Chapter 803 or § 814.104(a)(1), Government Code, has at least 10 years of eligible service credit, and is at least 65 years of age;
(C) receives or is eligible to receive an annuity that is based on eligibility under § 814.002, 814.102, 814.104(b), 814.107(a), 834.101, or 839.101 or Subchapter B, Chapter 840A, Government Code; or
(D) receives or is eligible to receive an annuity under Subchapter B, Chapter 820, Government Code, and has at least 10 years of eligible service credit.

(c) An individual is eligible to participate in the group benefits program as provided by Subsection (a) if:
(1) the individual retires under the jurisdiction of the Teacher Retirement System of Texas and has at least 10 years of eligible service credit, including not more than five years of military service credited in the Employees Retirement System of Texas, or has five years of eligible service credit and is the sole surviving spouse of military personnel who was killed in action;
(2) the individual:
(A) has accumulated eligible service credit in an amount so that the sum of the person‘s age and amount of service credit, including months of age and credit, equals or exceeds the number 80; or
(B) is at least 65 years of age; and
(3) the individual was employed, as the last state employment before retirement, including employment by a public junior college, by a state agency whose employees are authorized to participate in the group benefits program.
(c-1) An individual is eligible to participate in the group benefits program as provided by Subsection (a) if:
(1) the individual meets the minimum requirements under Subsection (c) except that the individual does not have at least 10 years of eligible service credit as described by Subsection (c)(1);
(2) the individual has at least 10 years of combined service in a position for which the individual was eligible to participate in the group benefits program or in the uniform program under § 1601.101; and
(3) either:
(A) the individual’s greatest number of years of state employment was in a position for which the individual was eligible to participate in the group benefits program; or
(B) if the individual’s years of employment in positions eligible to participate in the group benefits program and the uniform program are equal, the individual’s last state employment before retirement was in a position for which the individual was eligible to participate in the group benefits program.
(c-2) An individual is eligible to participate in the group benefits program as provided by Subsection (a) if the individual:
(1) was employed for at least 10 years by a school district established as specified by § 19.002, Education Code, as the individual’s last position of employment before retirement;
(2) has at least:
(A) 10 years of eligible service credit, including not more than five years of military service credited in the Employees Retirement System of Texas; or
(B) five years of eligible service credit and is the sole surviving spouse of military personnel who was killed in action; and
(3) retires under the jurisdiction of the Teacher Retirement System of Texas and:
(A) has accumulated membership service credit as provided by § 823.201(a), Government Code, in an amount so that the sum of the person’s age and amount of membership service credit, including months of age and credit, equals or exceeds the number 80; or
(B) is at least 65 years of age.
(d) An individual is eligible to participate in the group benefits program as provided by Subsection (a) if:
(1) the individual retires under the optional retirement program established by Chapter 830, Government Code;
(2) the individual has at least 10 years of eligible service credit; and
(3) the individual:
(A) is at least 65 years of age, or would have been eligible to retire and receive a service or disability retirement annuity from the Teacher Retirement System of Texas or the Employees Retirement System of Texas in an amount such that the sum of the person’s age and amount of service credit, including months of age and credit, equals or exceeds the number 80 or would have been eligible to retire and receive a disability retirement annuity from the Teacher Retirement System of Texas or the Employees Retirement System of Texas, if the individual had not elected to participate in the optional retirement program, and is eligible to receive an annuity or periodic distribution of funds from an account under the optional retirement program; or
(B) is disabled as determined by the Employees Retirement System of Texas based on at least 10 years of eligible service credit, and is receiving an annuity or periodic distribution of funds from an account under the optional retirement program.
(e) An individual is eligible to participate in the group benefits program as provided by Subsection (a) if the individual retired under Subtitle C, Title 8, Government Code, before September 1, 1991, with at least five and less than 10 years of service credit.
(f) An individual is eligible to participate in the group benefits program if the individual is certified and qualified as disabled and receives or is eligible to receive an annuity under Section 814.202, 814.207, 824.302, only as to higher education, or 839.201, Government Code.
(g) An individual is eligible to participate in the group benefits program as provided by Subsection (a) if the individual is at least 65 years of age and retires under a federal or state statutory retirement program not described by another provision of this section, to which an institution of higher education has made employer contributions, and the individual has met service requirements, age requirements, and other applicable requirements comparable to the requirements for retirement under the Teacher Retirement System of Texas, based on at least 10 years of service credit.
(h) A person eligible to participate and participating in the group benefits program as an annuitant on September 1, 2003, may continue to participate in the program as an annuitant if a lapse in coverage has not occurred.
(i) Subject to § 1551.323, an individual and the individual’s dependents are eligible to participate in the group benefits program as an annuitant and the dependents of an annuitant if the individual:
(1) served in a position for which the individual was eligible to participate in the group benefits program under § 1551.101 on or before August 31, 2003; and
(2) at the time of retirement meets the requirements for eligibility for participation in the program as an annuitant as those requirements existed on August 31, 2003.