California Code, Revenue and Taxation Code - RTC § 538

(a) If the assessor believes that a specific provision of the Constitution of the State of California, of this division, or of a rule or regulation of the board is unconstitutional or invalid, and as a result thereof concludes that property should be assessed in a manner contrary to such provision, or the assessor proposes to adopt general interpretation of a specific provision of the Constitution of the State of California, or this division, or of a rule or regulation of the board, that would result in a denial to five or more assessees in that county of an exemption, in whole or in part, of their property from property taxation, the assessor shall, in lieu of making such an assessment, bring an action for declaratory relief against the board under Section 1060 of the Code of Civil Procedure. The court shall allow intervention in such action by potential assessees and other assessors under Section 387 of the Code of Civil Procedure to the greatest extent practicable.

(b) If the assessor obtains judgment in such action upholding the validity of such assessment, the assessor shall correct the roll in accordance with Section 4831 consistent with such judgment within 60 days of the date upon which the judgment becomes final, regardless of the time limit otherwise provided in Section 4831. The assessor shall not levy an assessment based upon the subject matter of the action under any other section of this division.

(c) Within 60 days of notice of such assessment, a person assessed under subdivision (b) may file a claim for refund relating to the assessment of any of the person's property for the fiscal year to which the assessment under subdivision (b) relates regardless of the time limit otherwise provided in Section 5097.