Cal. Gov. Code § 25502.3

In counties having a population of less than 200,000, the board of supervisors may authorize the purchasing agent to engage independent contractors to perform services for the county or county officers, with or without the furnishing of material, when the annual aggregate cost does not exceed fifty thousand dollars ($50,000), except that this amount shall be adjusted annually by any annual increase in the California Consumer Price Index as determined pursuant to Section 2212 of the Revenue and Taxation Code.