What is Proposition 8?
The California law that lets you pay taxes on what your home is actually worth — not what the county thinks it's worth.
The basics
In 1978, California voters passed two landmark property tax measures. Most people know about Proposition 13, passed in June, which caps how much your assessed value can increase each year (no more than 2%). But fewer people know about its counterpart, Proposition 8, passed that November.
Prop 8 works in the opposite direction. When your home's current market value drops below your assessed value — the Prop 13 base year value trended forward at up to 2% per year — you have the legal right to a temporary reassessment to the lower market value.
In plain terms: your property taxes go down to reflect what your home is actually worth right now, not what the county's formula says it should be.
The reassessment is temporary. When market values recover past your Prop 13 base, your assessed value goes back up — but it's still capped at the Prop 13 limit. There's no penalty for having received the lower assessment.
Example
If your assessed value is $850,000 but comparable homes in your neighborhood are selling for $650,000, you shouldn't be taxed on $850,000. Prop 8 gives you the right to request a reassessment to the lower value — potentially saving you $2,200+/year in property taxes.
How do you know if you qualify?
The core question is simple: is your home's current market value lower than your current assessed value? If yes, you likely qualify for a Prop 8 reduction.
This commonly happens when:
- Market downturns — home prices in your area have declined since your last assessment
- Local price corrections — your neighborhood has seen price softening even if the broader market hasn't
- Assessment creep — your assessment has been trending up at 2% per year while the market hasn't kept pace
- Neighborhood changes — factors like new construction, zoning shifts, or other local conditions have affected property values
The county reviews some properties automatically, but their review may not catch every overassessment. We go deeper — analyzing more comps with professional-grade adjustments to find savings others miss.
What happens after a Prop 8 reduction?
Once your Prop 8 reassessment is approved, your property taxes drop for the current tax year. But it's worth understanding what happens next.
Your taxes drop
Your property tax bill is recalculated based on the lower assessed value. The savings apply to the current tax year.
Annual review continues
The assessor reviews your property each year going forward, comparing your assessed value to current market conditions.
Values can recover
When market values rise past your Prop 13 base year value, your assessed value reverts to the Prop 13 amount. No penalty, no catch. One thing to know: while your assessment is temporarily reduced, it can increase by more than 2% in a single year as the market recovers — but it will never go above your original Prop 13 base year value. Once it reverts, the normal 2% annual cap applies again.
You can file again
If the market dips again in future years, you can file for another Prop 8 reduction. There's no limit on how many times you can request a reassessment.
How to file a Prop 8 appeal
Filing a property tax appeal involves submitting evidence of comparable sales to your county assessor. The evidence needs to show that homes similar to yours — in size, condition, location, and features — have recently sold for less than your assessed value.
In Alameda County, there are two paths: an informal review process (free, no hearing required) and a formal appeal through the Assessment Appeals Board. Most homeowners start with the informal process because it's faster and less involved.
Free. 60 seconds. No signup required.
Most homeowners don't know Prop 8 exists. If your home's market value has dropped, you may be paying more than you need to.
It takes about 60 seconds
Overassessed provides estimates based on publicly available data and AI-generated analysis. This is not a formal appraisal, legal advice, or tax advice. Results are not guaranteed, and appeal outcomes depend on county review. Users file their own appeals. AI-generated estimates may differ from actual market values.