California Code, Revenue and Taxation Code - RTC § 18416

(a) Unless expressly otherwise provided in this part, any notice may be given by first-class mail postage prepaid.

(b) For purposes of this part, any notice mailed to a taxpayer shall be sufficient if mailed to the taxpayer's last known address.

(c) The last known address shall be the address that appears on the taxpayer's last return filed with the Franchise Tax Board, unless the taxpayer has provided to the Franchise Tax Board clear and concise written or electronic notification of a different address, or the Franchise Tax Board has an address it has reason to believe is the most current address for the taxpayer.