California Code, Elections Code - ELEC § 3102

(a) Any voter who qualifies as a military or overseas voter pursuant to subdivision (b) of Section 300 shall have the right to register for, and to vote in, any election within the state, including any general, special, or primary election for any federal or statewide office or state ballot measure that is voted on statewide. Any voter who qualifies as a military or overseas voter pursuant to subdivision (b) of Section 300 shall also have the right to register for, and to vote in, any other election for any office or ballot measure held in the precinct in which the voter was a resident when the voter was last living within the territorial limits of the United States or the District of Columbia, or, for a military or overseas voter qualified pursuant to paragraph (2) of subdivision (b) of Section 321, in any precinct of the state in which the voter's parent or legal guardian resided when the parent or legal guardian last lived within the territorial limits of the United States or the District of Columbia.

(b) When a military or overseas voter registers to vote, the application shall be completed by the voter and shall contain the voter's name; the voter's date of birth; the address of the voter's residence in the state when the voter was last living within the territorial limits of the United States or the District of Columbia or, if qualified as a military or overseas voter pursuant to paragraph (2) of subdivision (b) of Section 321, the address of the voter's parent or legal guardian when the parent or legal guardian was last living within the territorial limits of the United States or the District of Columbia; the address to which the ballot is to be sent; the voter's political party preference or a statement that the voter declines to disclose a political party preference; and the voter's signature.

(c) If an elections official receives a completed federal postcard application from a person qualified as a military or overseas voter, the application shall be deemed to be an affidavit of registration.

(d) If the applicant is not a resident of the county to which the applicant has applied, the elections official receiving an application from a military or overseas voter shall forward it immediately to the county in which the applicant resided when the applicant was last living within the territorial limits of the United States or the District of Columbia or, for a military or overseas voter qualified pursuant to paragraph (2) of subdivision (b) of Section 321, to the county in which the applicant's parent or legal guardian resided when the parent or legal guardian last lived within the territorial limits of the United States or the District of Columbia.

(e) An application made pursuant to this section that is received by the elections official having jurisdiction over the election and deemed to be an affidavit of registration shall be effective only if it is postmarked on or before the 15th day prior to the election.