California Regulations § 19052 Official Affidavits

Only those affidavits of registration provided by the Secretary of State through the county clerks shall be used for the registration of voters pursuant to Elections Code Section 301 . Such voter registration cards shall not be altered, defaced, or changed in any way, other than by the insertion of a mailing address and the affixing of postage, if mailed, or as otherwise specifically authorized by the Secretary of State, prior to distribution to prospective registrants, nor shall the affidavit portion of the voter registration cards be marked, stamped, or partially or fully completed by anyone other than an elector attempting to register to vote or by another person assisting such elector after being requested by such elector to assist in completing the affidavit.