Assessed Value vs. Market Value: Why the Gap Means You May Be Overpaying

Your property tax bill is driven by your assessed value — but the number that actually matters for an appeal is your market value. When the two drift apart, you may be paying more than your fair share.

The two numbers

• Assessed value: the value the county Assessor places on your property for tax purposes. In California it's anchored by your Proposition 13 base year; in Washington it's reset to market each year.
• Market value: what your property would actually sell for today, in an arms-length sale.

When the market is rising, these track closely. When values fall — or the Assessor's records are stale or wrong — a gap opens, and you can be assessed above what your home is really worth.

Why the gap happens

• Assessors value properties in bulk and can't re-inspect each one every year.
• A market downturn isn't reflected automatically (in California you must request a Prop 8 reduction).
• Record errors — wrong square footage, bed/bath count, or condition — inflate the assessment.

How to check if you're overpaying

1. Find your assessed value on your tax bill or your assessment notice. (How to read it.)
2. Estimate market value from recent comparable sales — similar homes that sold near the January 1 valuation date. Don't rely on a Zillow "Zestimate"; assessors and appeal boards don't accept it.
3. If market value is clearly below assessed value, you likely have an appeal worth filing.

That comparison — your home against the right comps — is exactly what an appeal turns on, and what CompFinder builds for you. A meaningful gap is real money: roughly $1,200/year per $100,000 in California.