Riverside County said property owners who believe the market value of their property on Jan. 1, 2026, is lower than its assessed value must submit a Decline-in-Value Reassessment Application, also called a Request for Review, by Monday, Nov. 2, 2026.

The county said the regular deadline is Nov. 1 but, because it falls on a Sunday this year, the deadline extends to the next business day.

The Request for Review lets the Riverside County Assessor-Clerk-Recorder evaluate whether a property qualifies for a temporary reduction under Proposition 8; the county said a property may qualify when its market value as of Jan. 1 is lower than its assessed value.

Property owners who want to formally challenge an assessed value must file an Assessment Appeal Application by Nov. 30, 2026, with the Riverside County Clerk of the Board; the county said information about the appeal process and online filing is available through the Assessment Appeals Division.

The county said the Request for Review and the Assessment Appeal are separate processes; filing a Decline-in-Value Reassessment Application with the Assessor does not replace or extend the deadline to file a formal assessment appeal.

The county said the Assessor expects to complete reviews well in advance of the Nov. 30 appeal deadline; however, if a review has not been completed by that time the appeal deadline is not extended and property owners may still file an appeal to preserve their right to formally challenge the assessment.

The county said property owners should continue to pay their property tax bills as issued while a review or appeal is pending; if an assessment is reduced any resulting adjustment or refund will be processed accordingly.

The county said properties that received a Decline-in-Value reassessment last year are automatically included in the Assessor’s annual review; a new application is necessary only if the owner disagrees with the assessed value and wants another review.

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County of Riverside

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