In this subchapter:
(1) “Employee tax” means the tax imposed by Section 3101 of the Internal Revenue Code of 1986 (26 U.S.C. § 3101).
(2) “Employment” means service performed by a state employee except service:
(A) that in the absence of an agreement under this subchapter would constitute employment under the Social Security Act; or
(B) that under the Social Security Act may not be included in an agreement between the retirement system and the secretary.
(3) “State agency” means:
(A) a department, commission, board, office, or other agency in the executive or legislative branch created by the constitution or a statute of this state;
(B) the supreme court, the court of criminal appeals, a court of appeals, or the Texas Judicial Council; or
(C) a university system or an institution of higher education as defined by § 61.003, Education Code.
(4) “State employee” includes an elected or appointed state officer but does not include an individual who:
(A) is compensated by fees; or
(B) is in a position eligible for membership in the Teacher Retirement System of Texas unless the person is employed by a state department, agency, or institution.
(5) “Wages” means all remuneration for employment, including the cash value of all remuneration paid other than by cash, except for remuneration that does not constitute “wages” under the Federal Insurance Contributions Act.