(a) Employment of a person by a single 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 regular, full-time service eligible for membership.
(b) Any employee of a public state-supported educational institution in Texas shall be considered to meet the requirements of subsection (a) of this section if his or her customary employment with a single employer is for 20 hours or more for each week and for four and one-half months or more.
(c) 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.
(d) For purposes of subsection (a) of this section, full-time service is employment that is usually 40 clock hours per week. If the TRS-covered employer has established a lesser requirement for full-time employment for specified positions that is not substantially less than 40 hours per week, full-time service includes employment in those positions. In no event may full-time employment require less than 30 hours per week.
(e) Beginning on the first day of the 2011-2012 school year and thereafter:
  (1) Except as provided in subsection (j) of this section regarding adjunct faculty, if there is no equivalent full-time position of a given position, the minimum number of hours required per week that will qualify the position for TRS membership is 15.
  (2) The requirement in this subsection applies to all positions, including bus drivers.
(f) For school years prior to the 2011-2012 school year:
  (1) If there is no equivalent full-time position of a given non-certified position, the minimum number of hours required per week that will qualify the position for TRS membership is 15.
  (2) If there is no equivalent full-time position of a given certified position, the minimum number of hours required per week that will qualify the position for TRS membership is 20.
  (3) Persons regularly employed as bus drivers for routes approved by the Transportation Department of the Texas Education Agency are eligible for membership. A person will be considered regularly employed as a bus driver if his or her customary employment requires driving at least one such route per day.
(g) For purposes of subsection (a) of this section, regular employment is employment that is expected to continue for four and one-half months or more. Employment with an institution of higher education (including community and junior colleges) is regular employment if it is expected to continue for more than one full semester or continues for more than one full semester in the same school year. Employment that is expected to continue for less than four and one-half months or for no more than one full semester in a school year is temporary employment and is not eligible for membership.
(h) For purposes of subsection (a) of this section, a rate of compensation is comparable to other persons employed in similar positions if the rate of compensation is within the range of pay established by the Board of Trustees for other similarly situated employees or is the customary rate of pay for persons employed by that employer in similar positions.
(i) For purposes of this section, employment in institutions of higher education (including community and junior colleges) as an instructor of classes taken by students for college credit or classes that are taken to prepare students for college level work, that are measured or expressed in terms of the number of courses; semester or course hours/credits; instructional units; or other units of time representing class or instructional time must be converted to clock hours and counted as a minimum of two clock hours for each clock hour of instruction or time in the classroom or lab in order to reflect instructional time as well as preparation, grading, and other time typically associated with one hour of instruction. If the employer has established a greater amount of preparation time for each hour in the classroom or lab, the employer's standard will be used to determine the number of clock hours scheduled for work. Employment as an instructor of an on-line class taken by students for college credit that is measured or expressed in terms of the number of courses; semester or course hours/credits; instructional units; or other units of time representing class or instructional time must be counted as a minimum of two clock hours for each course hour or semester hour. Employment as an instructor of continuing education, adult education, and/or classes offered to employers or businesses for employee training, that is not measured or expressed in terms of the number of courses; semester or course hours/credits; or instructional units or other units of time rather than clock hours and for which the students/participants do not receive college credit must be considered for membership based on the number of clock hours worked.
(j) Beginning on the first day of the 2013-2014 school year, the minimum number of hours required per week that will qualify an adjunct faculty position for TRS membership is 20. Effective with the beginning of the 2015-2016 school year, the minimum number of hours per week that will qualify an adjunct faculty position as eligible for membership in TRS must be served with a single employer or must meet the requirements of §25.6 of this title (relating to Part-time or Temporary Employment). For purposes of this section, an adjunct faculty position is an instructor position that is filled on a semester-by-semester basis, compensated on a per class basis, and the duties include only those directly related to instruction of students in a class taken by students for college credit or taken to prepare students for college level work. If a person combines work as an adjunct faculty instructor and any other type of employment, the minimum number of hours worked per week that will qualify the person for membership is 20.
(k) A person employed by an open enrollment charter school authorized under Subchapter D, Chapter 12, Education Code, or the open enrollment charter holder is eligible for membership in TRS if the person is performing services on behalf of the Texas open enrollment charter school and the employment otherwise meets the requirements of this section. A person employed by a management company or other entity retained by the charter school or charter holder to provide management or other services on behalf of the open enrollment charter school is not eligible for membership in TRS.
(l) A person employed by a Texas public school district and performing services on behalf of a campus or program charter school authorized under Subchapter C, Chapter 12, Education Code, is eligible for membership in TRS if the employment otherwise meets the requirements of this section. An employee of an open enrollment charter holder that is contracted to provide services to a campus or program charter school is eligible for membership in TRS if the person is performing services on behalf of the campus or program charter school and the employment otherwise meets the requirements of this section. An employee of a management company or other entity retained to provide management or other services on behalf of the campus or program charter school is not eligible for membership in TRS.
(m) Beginning on September 1, 2015, if an employee is employed in two or more part-time positions with a single employer, the minimum number of hours the employee must work in all positions in order to establish eligibility for membership in TRS must equal or exceed one-half of the hours required for the full-time equivalent position requiring the greater number of hours per week.

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; amended to be effective March 8, 2007, 32 TexReg 1078; amended to be effective April 1, 2011, 36 TexReg 1828; amended to be effective June 3, 2013, 38 TexReg 3652; amended to be effective August 15, 2013, 38 TexReg 5110; amended to be effective July 17, 2014, 39 TexReg 5430; amended to be effective December 22, 2014, 39 TexReg 10021; amended to be effective January 1,2016, 40 TexReg 9724