(a) A county or municipality may supplement, from its own funds, the salary of a department employee whose duties include providing services as part of, or relating to, the provision of child protective services and adult protective services by the department.
(b) A department employee who has worked in the same position for the department in a different region is not eligible for a salary supplement under Subsection (a) for a minimum of six months after assuming the position in the new region.
(c) Section 659.020, Government Code, does not apply to the supplement authorized by this section.
(d) The department may not require a salary supplement as a condition for creating or maintaining a position in the region.