Section 2120 Of Article 1. General Provisions From California Elections Code >> Division 2. >> Chapter 2. >> Article 1.

. (a) If the county elections official receives a letter from a voter stating that the voter has moved to a new address in another county in the state and the voter provides the new address, the elections official shall immediately update the voter's registration and the former address shall be maintained with the voter record.
  (b) If the county elections official receives a letter from a voter stating that the voter has moved to a new address in another county in the state and the voter does not provide the new address, the elections official shall cancel the old registration for any election occurring at least 15 days after the receipt of the letter.