Proposition 8 (Decline-in-Value)
Proposition 8 is the California rule that allows a county to temporarily reduce a home's assessed value when its current market value falls below its factored base-year value on the January 1 lien date. The county then taxes the lower of the two figures until the market recovers.
Why it matters to a homeowner
Proposition 13 protects you in a rising market, but it offers no relief on its own when prices fall. Prop 8 fills that gap. If your home is worth less than the value on your tax bill, you may be paying more than you should, and a decline-in-value reduction is the fix.
A concrete example
Imagine your factored base-year value is $650,000, but comparable homes in your area are now selling for $560,000. Under Prop 8, the assessor can enroll the lower $560,000 figure for that tax year, trimming your bill. The reduction is temporary: in later years your assessed value can climb back up, but never above your factored base-year value (unless ownership changes or you build).
How it affects your assessment or appeal
A Prop 8 reduction is the most common reason a homeowner files an appeal. To win one, you show the assessor that your home's market value on the lien date was below the assessed value, usually with comparable sales. If the county already lowered your value, you may not need to appeal at all.
See the State Board of Equalization's official Decline in Value – Proposition 8 page for the governing rules.
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