California Code, Elections Code - ELEC § 10703

(a)(1) Except as provided in paragraph (2), a special election to fill a vacancy in the office of Representative in Congress, State Senator, or Member of the Assembly shall be conducted on a Tuesday at least 126 days, but not more than 140 days, following the issuance of an election proclamation by the Governor pursuant to Section 1773 of the Government Code.

(2) A special election to fill a vacancy in an office listed in paragraph (1) may be conducted within 200 days following the proclamation in order to consolidate the election or the primary election with an election occurring wholly or partially within the same territory in which the vacancy exists.