Cal. Rev. & Tax. Code § 531.9

A county board of supervisors may, by ordinance, prohibit an assessor from making an escape assessment of an appraisal unit where that assessment would result in an amount of taxes due which is less than the cost of assessing and collecting them. In no event may the ordinance apply to any escape assessment of an appraisal unit if the amount of taxes resulting from the escape assessment would exceed fifty dollars ($50).