Texas Government Code - GOV'T § 853.101. Creditable Prior Service

(1) service performed as an employee of a participating department of a municipality before the date the department's participation in the retirement system became effective;

(2) for a person who becomes a member of the retirement system under Section 852.105, service performed as an employee of a participating department during a time the person was ineligible for membership because of age;  or

(3) for a person entitled to prior service credit under Section 853.102(a)(3), service for which current service credit has not been granted that was performed as an employee of a participating department during a time the person was ineligible to participate because of age.