Local Government Code §84.002

(a) In a county with a population of 10,200 or more, the district judges shall appoint a county auditor. (b) In a county with a population of less than 10,200: (1) the district judges may appoint a county auditor if the judges determine that the county's financial circumstances warrant the appointment; and (2) the district judges shall appoint a county auditor if: (A) the commissioners court finds that a county auditor is necessary to carry out county business and enters an order in its minutes stating the reason for this finding; (B) the order is certified to the district judges; and (C) the district judges find the reason stated by the commissioners court to be good and sufficient.