Cal. Rev. & Tax. Code § 2615.5
When the county sends a tax bill or copy thereof to any homeowner who received the homeowners' exemption in the immediately preceding year, except where such person has transferred title in the property since the immediately preceding lien date, or to any person who has filed an exemption claim during the preceding assessment year, the tax bill or copy shall be accompanied by a notice concerning ineligibility for the homeowners' exemption. The notice shall inform the taxpayer of the circumstances under which he becomes ineligible for the exemption, of the penalties which are applicable if he allows the exemption to continue when he is not eligible for the exemption, and of his duty to inform the assessor when he is no longer eligible for the exemption. Failure to receive the notice shall not excuse the taxpayer of the duty to inform the assessor of his ineligibility for the exemption.
Ca. Rev. and Tax. Code § 2615.5