Cal. Elections Code § 2152

(a) Whenever any voter has declined to disclose or has changed the voter’s party preference prior to the close of registration for an election, the voter may either so disclose or have a change recorded by executing a new affidavit of registration and completing the prior registration portion of the affidavit. (b) From the 14th day immediately preceding an election until the close of polls on election day, in lieu of executing a new affidavit of registration to disclose or have a change recorded for a voter’s political party preference, the county elections official shall accept a written request by a voter that discloses or changes the voter’s political party preference and that contains all of the following: (1) The voter’s printed name. (2) The voter’s current residence address. (3) The voter’s new political party preference. (4) A certification by the voter of the content of the written request as to its truthfulness and correctness, under penalty of perjury. (5) The voter’s signature and date of execution. (c) The written request shall be delivered to the county elections official’s office or to any location that offers conditional voter registration and at which a ballot for the political party for which the voter disclosed a preference can be issued. Following delivery to such a location, the county elections official shall issue a ballot in accordance with the following: (1) A nonprovisional ballot shall be issued to the voter if either of the following applies: (A) The voter appears at the voter’s precinct, the voter’s name is found on the roster, and the voter either has not been issued a vote by mail ballot or the conditions set forth in subdivision (a) of Section 3015 are satisfied. (B) The voter appears at a location that is equipped with an electronic poll book or other means to determine the voter’s precinct, the location can provide the voter with a ballot for the voter’s precinct, the entire county has established connectivity between locations, and the location at which the voter appears verifies that the voter has not cast a ballot at another location for the election and notes in the voter’s record that the voter cast a ballot. (2) A provisional ballot shall be issued to the voter if either of the following applies: (A) The voter appears at the voter’s precinct, the voter’s name is found on the roster, the voter has been issued a vote by mail ballot, and the conditions set forth in subdivision (a) of Section 3015 are not satisfied. (B) The voter appears at a location, other than the voter’s precinct, that is equipped with an electronic poll book or other means to determine the voter’s precinct, but the entire county has not established connectivity between locations such that the location is unable to verify that the voter has not cast a ballot at another location for the election. (d) Upon receipt of a properly executed written request described in subdivision (b), the registration of the voter shall be immediately updated and the written request shall be maintained with the voter’s record.