34 Tex. Admin. Code § 25.1
Employment of a person by a TRS covered employer for one-half or more of the standard full-time work load at a rate comparable to the rate of compensation for other persons employed in similar positions is defined as regular, full-time service eligible for membership. Any employee of a public state-supported educational institution in Texas shall be considered to meet the requirements of the preceding sentence if his or her customary employment is for 20 hours or more for each week and for four and one-half months or more in one school year. Membership eligibility for positions requiring a varied work schedule is based on the average of the number of hours worked per week in a calendar month and the average number of hours worked must equal or exceed one-half of the hours required for a similar full-time position. If there is no full-time equivalent of a given non-certified position, the minimum number of hours required per week that will qualify the position for TRS membership is 15. If there is no full-time equivalent of a given certified position, the minimum number of hours required per week that will qualify the position for TRS membership is 20.
Source Note:The provisions of this §25.1 adopted to be effective January 1, 1976; amended to be effective June 1, 1995, 20 TexReg 3733; amended to be effective June 15, 1999, 24 TexReg 4454; amended to be effective March 12, 2003, 28 TexReg 2093; amended to be effective October 25, 2006, 31 TexReg 8728.