Cal. Gov. Code § 27012

The Controller may summon county treasurers or the authorized representative of any county treasurer to meet with the Controller or his or her duly authorized representatives, in those groups and at that place or those places within the state as may be designated by the Controller for the purpose of discussing the interpretation, procedures, uniformity of operation, and efficient administration of the Revenue and Taxation Code and the Government Code. The actual and necessary expenses of any county officer or his or her authorized representative that are incurred while traveling to and from or while attending any meeting called pursuant to this section by the Controller shall be a charge against the county, to be paid in the same manner as other county charges are paid, provided that prior approval of the board of supervisors has been obtained.