Texas Government Code - GOV'T § 814.002. Benefits From Both Membership Classes

(a) If a member has service credit in both classes of membership, is eligible to retire from one class, and does not hold a position included in the other class, the member may retire from both classes and receive benefits based on all service credited in the retirement system.

(b) If a member is retiring and uses service credited in a class of membership to meet a length-of-service requirement for retirement, the member must retire from that class.