California Code, Revenue and Taxation Code - RTC § 252

When making the first claim any person claiming the veterans' exemption, or the spouse, legal guardian, or conservator of such person, or one who has been granted a power of attorney by such person, shall appear before the assessor, shall give all information required and answer all questions in an affidavit prescribed by the State Board of Equalization, and shall subscribe and swear to the affidavit before the assessor. The assessor may require other proof of the facts stated before allowing the exemption. In subsequent years the person claiming the veterans' exemption, or the spouse, legal guardian, or conservator of such person, or one who has been granted a power of attorney by such person, may file the affidavit under penalty of perjury by mail.

Where a claim is filed by a legal guardian or conservator of a person claiming the veterans' exemption, or one who has been granted a power of attorney by such claimant, the person filing the affidavit shall declare that he has sufficient knowledge of the financial affairs of the claimant to give all information required and answer all questions in the affidavit under penalty of perjury.