Cal. GOV § 3107

No compensation nor reimbursement for expenses incurred shall be paid to any disaster service worker by any public agency unless such disaster service worker has taken and subscribed to the oath or affirmation required by this chapter. It shall be the duty of the person certifying to public payrolls to ascertain and certify that such disaster service worker has taken such oath or affirmation. Whenever there is more than one officer certifying to public payrolls the governing body of a city or county or school district may designate and make it the duty of a certain officer or officers to ascertain and certify that such disaster service worker has taken such oath or affirmation. The governing body of a city or county or school district may designate and make it the duty of a local disaster service officer to ascertain and certify that each volunteer disaster service worker has taken such oath or affirmation.

Nothing in this chapter, however, shall prevent the correction of any technical error or deficiency in an oath taken pursuant to this chapter; provided, such correction is made before the disaster service worker is actually paid or reimbursed.