California Code, Revenue and Taxation Code - RTC § 6487.05

(a) Notwithstanding Section 6487, the period during which a deficiency determination may be served to a qualifying retailer is limited to three years after the last day of the calendar month following the quarterly period for which the amount is proposed to be determined. For purposes of this section, a “qualifying retailer” is a retailer that meets all of the following conditions:

(b) If the department or its designee finds that the retailer's failure to make a timely return or payment is due to reasonable cause and circumstances beyond the retailer's control, and occurred notwithstanding the exercise of ordinary care and the absence of willful neglect, the retailer shall be relieved of the penalties imposed pursuant to this part. Any retailer seeking relief of penalty shall file a statement under penalty of perjury setting forth the facts upon which they base their claim for relief.