California Code, Revenue and Taxation Code - RTC § 8996

(1) For amounts disclosed on a return received by the board before the date the return is delinquent, the date the return would have been delinquent;

(2) For amounts disclosed on a return filed on or after the date the return is delinquent, the date the return is received by the board;

(3) For amounts determined under Section 8826 (pertaining to jeopardy assessments), the date the notice of the board's finding is mailed or issued;

(4) For all other amounts, the date the assessment is final.