http://assessor.co.kern.ca.us/assessor/property_valuation.cfm

PROPOSITION 8 (DECLINE IN VALUE): 
Proposition 8 allows the Assessor to review both the factored base-year value and the current market value of a property as of January 1 of each year and enroll the lesser value. When the current market value replaces the higher Proposition 13 value, that lower value is commonly referred to as a "Prop 8 Value". In no circumstance can the Assessor value a property higher than its Proposition 13 factored base-year value.
 
Although the annual increase for Proposition 13 values is limited to no more than 2%, the same restriction does not apply to values adjusted under Proposition 8. Actual market value must be enrolled as a Proposition 8 value and any subsequent increase or decrease in market value is enrolled regardless of its percentage. However, when the current market value of a Proposition 8 property exceeds its factored Proposition 13 base-year value, the Assessor simply reinstates the factored Proposition 13 value.
 
Property owners who feel that their assessed value exceeds current market value should contact our office and request a Proposition 8 review. The last day to request a Proposition 8 review of the assessment on the current tax bill is October 30. Requests made after October 30 will apply to the upcoming tax year. Owners may also elect to file a formal assessment appeal during the open filing period.