Texas Local Government Code - LOC GOV'T § 158.010. Employment By Departments

(a) The head of each department included in the coverage of a county civil service system may assume responsibility for selecting all persons who are to be employees of that department.

(b) A person employed by a department whose head has assumed responsibility as provided by Subsection (a) serves as a probationary employee during the first six months after selection and may not be included in the coverage of the county civil service system during that six-month period. At the end of the six-month period the person's employment may be terminated or the person may be made a permanent employee by the head of the department.

(c) On becoming a permanent employee, a person comes under the coverage of the county civil service system and is fully entitled to all benefits of and subject to all obligations imposed by the system.

(d) This section does not affect the status of any person who is an employee of a department under a county civil service system on the date the head of the department assumes responsibility for selecting persons who are to be employees of that department.

(e) The rules adopted by the commission under Section 158.009 relating to the selection and classification of county employees and to competitive examinations for selection apply to the initial hiring of personnel under this section.