California Code, Revenue and Taxation Code - RTC § 4808

Notwithstanding any provision of law to the contrary, any taxpayer may, no later than 30 days after the delinquency date of a property tax bill or any installment thereof, seek declaratory relief in the superior court in the county in which the property is located alleging that the locally assessed property taxes have been illegally or unconstitutionally assessed or collected or are to be so assessed or collected.

Any action alleging an illegal or unconstitutional method of valuation or similar matter shall name as respondent the assessor of the county in which the property is located.  An action alleging an unconstitutional or illegal tax rate shall name as respondent the auditor-controller of such county.  In the event the action involves the validity of a rule or regulation adopted by the State Board of Equalization, the board shall be named as a respondent.  The relief granted pursuant to this section shall be limited to a declaration that the taxes assessed or collected or to be assessed or collected are unconstitutional or otherwise legally invalid.

This section shall not be interpreted to allow a taxpayer to postpone payment of property taxes pending the decision of the court.  All assessment and collection provisions of this division shall continue to apply to properties affected by this section.

This section shall be applicable only in instances where the alleged illegal or unconstitutional assessment or collection occurs as the direct result of a change in administrative regulations or statutory or constitutional law that became effective not more than 12 months prior to the date the action is initiated by the taxpayer.

The procedure for obtaining a declaratory relief judgment under this section shall be the same as that used to obtain a writ of mandate.