California Code, Revenue and Taxation Code - RTC § 4836

(a) If the correction will result in a reduction of an assessment that would entitle the assessee to a refund, the auditor shall either process the refund or notify the assessee in writing of the requirements for obtaining a refund pursuant to Section 5097.  The notice shall state that the assessee is entitled to a refund and that a claim for a refund shall be filed, pursuant to Section 5097, within 60 days of the date of the notice.  Notwithstanding Section 5097, a claim for a refund shall be deemed timely filed if it is filed within 60 days of the date of the notice.

(b) If the correction will increase the amount of unpaid taxes, the assessor shall notify the assessee of the procedure for obtaining review by the county board under Section 1605 and the procedure for applying for cancellation under Section 4986.