Assessment Ratio
100% (Prop 13)
Appeal Deadline
Jul 2 - Nov 30, 2026
Official Form
BOE-305-AH
Risk of Increase
No
How Assessment Works in California
Under Proposition 13, California properties are assessed at their purchase price (base year value) plus a maximum 2% annual increase. Your assessed value can only be reduced if the current market value falls below your factored base year value. This means protests are most effective during market downturns.
How to File in California
File with your county Assessment Appeals Board by mail or in person. Some counties accept online filings. The filing window is July 2 through November 30 (or September 15 in some counties).
Step-by-Step
California Appeal Process
Review your annual assessment notice (mailed in July) showing your property's assessed value.
Compare your assessed value to current market conditions. If market values have declined below your factored base year value, you have a "decline in value" claim.
File Form BOE-305-AH (Assessment Appeal Application) with your county clerk of the Assessment Appeals Board.
Gather evidence: recent comparable sales, a professional appraisal, or market data showing decline.
Attend the hearing before the Assessment Appeals Board and present your evidence.
The board will issue a decision. If granted, your assessed value is reduced, and you receive a tax refund for any overpayment.
FAQ
California Property Tax Appeal Questions
How does Proposition 13 affect my appeal?
Prop 13 caps your assessed value increase to 2% per year from your purchase price. You can only appeal if the current market value is lower than your factored base year value (purchase price plus accumulated 2% increases). During market downturns, this creates significant savings opportunities.
What is a "decline in value" claim?
A decline in value (Prop 8) claim argues that your property's current market value has fallen below its Prop 13 factored base year value. If granted, your assessment is temporarily reduced. When the market recovers, the assessor can restore the value up to the Prop 13 limit.
Can my California assessment go up if I appeal?
No. The Assessment Appeals Board cannot raise your assessment above the value on the current roll. The worst outcome is that your value stays the same.