Assessed Value vs. Appraised Value in California: Why a Long-Held Claremont House Shows a Gap

Assessed value and appraised value answer different questions, so a gap between them is built into California law. Assessed value is the taxable value the Los Angeles County Assessor enrolls for a Claremont house, and it is not an appraisal: under Revenue and Taxation Code section 51 it is the lesser of the house's factored base year value and its full cash value on the January 1 lien date. Appraised value is an appraiser's opinion of market value as of a stated date. On a house that has stayed in one family for decades, the first number is anchored to a purchase long ago and the second to today's sales, which is why the two can sit far apart.

Where does the assessor's number come from?

It starts with base year value, the value the law fixes for a property at a starting point. Section 110.1 sets that starting point as the 1975 lien date, or, for property bought, newly built or otherwise changed in ownership after that, the date of the purchase or change in ownership, or the date new construction is completed. The rule traces to Article XIII A, section 2 of the California Constitution.

Each year after that, section 51 compounds the base year value by an inflation factor tied to the California Consumer Price Index, with an annual ceiling written into the statute. The result is the factored base year value. Section 51 then compares it with full cash value, the amount of cash or its equivalent the property would bring on the open market when neither buyer nor seller can take advantage of the other (section 110), and enrolls the lesser of the two.

So the assessed value is a formula applied to a starting value. It is set by the Los Angeles County Office of the Assessor for tax purposes, from records, without anyone walking through the house.

Where does the appraiser's number come from?

Appraised value, the value conclusion a licensed appraiser reports after developing an opinion of market value under the Uniform Standards of Professional Appraisal Practice (USPAP), comes from closed sales of similar houses. It is tied to an effective date, the date the opinion applies to, and an intended use, what the report will be used for. The appraiser inspects the house, measures gross living area, the finished space above grade, and adjusts each comparable sale for differences in size, condition, lot and location. Nothing in that process looks at the year the owner bought the house.

Why does the gap grow on a long-held Claremont house?

Because the factor that steps the base year value up each year has a ceiling, and the market does not. When sales prices in a pocket rise faster than the factor allows over many years, the factored base year value falls further behind the market each year the house is held. When the market falls, section 51 lets the assessed value follow full cash value down instead.

Claremont has a lot of the housing where that plays out. These are the kinds of properties that come in:

• Pre-1940 houses near the Village and the Colleges, along Indian Hill Boulevard and College Avenue: Craftsman bungalows, Spanish Colonial Revival and earlier houses, the kind of long-held property that reaches estates and trusts.
• Postwar ranch tracts north of Foothill Boulevard, reaching toward Base Line Road, on wider lots, where garage conversions and permit history on additions drive the adjustments.

Two similar houses on the same block can carry very different assessed values simply because one sold recently and one did not. Their market values, as buyers would weigh them, may be close. The Claremont area page describes these pockets in more detail.

Additions complicate the record. Completed new construction, such as a permitted addition or ADU, gets its own base year value as of completion under section 110.1. A porch enclosed long ago without a permit may not appear in the county's record at all, while the appraiser measures the house as it stands and notes the permit history.

What does the gap not mean?

• It does not mean the assessment is wrong. A low assessed value on a long-held house is the statute working as written.
• It is not evidence of market value. A buyer, a lender or a court looking for market value does not use the assessed value, because it is anchored to a past date by design.
• It does not carry over to the next owner automatically. A purchase or other change in ownership generally sets a new base year value. Exclusions exist for some transfers; the Assessor's office explains them, and your CPA or attorney decides how they apply.

When does the gap matter to an owner or an estate?

Long-held Village and north-of-Foothill houses often reach estates and trusts. A trustee, an executor or a CPA then needs market value as of the date of death, which is a retrospective appraisal, an appraisal whose effective date is in the past. The assessed value cannot stand in for it. The estate and date-of-death appraisal service and date-of-death appraisals explained plainly cover that assignment.

The gap also runs the other way. If the market value on January 1, the lien date set by section 2192, falls below the factored base year value, section 51 makes the lower figure the taxable value. The Assessor's decline-in-value review page explains how to ask for a review; confirm the current filing period there. An appraisal for that purpose is described under property tax appeal appraisal, and the county, not the appraiser, decides what value is enrolled.

What about the other numbers on the table?

An automated estimate from a website is not an appraisal; it is a statistical estimate made without seeing the house. An agent's comparative market analysis, or CMA, a licensed agent's opinion of a likely list or sale price, is not an appraisal. A cash offer is not an appraisal either; it is one buyer's price on stated terms. Mr. Cali Offers, a separate cash-offer brand that shares the Mr. Cali name, explains its offers at mrcalioffers.com/home-value.

For all of these side by side, see market, appraised, assessed value and a cash offer. For the county side, base year value explained walks through the Los Angeles County rule step by step, and appraiser vs. assessor compares the two jobs. The rest of the cluster is in the value types knowledge center.

If you need market value for a long-held house and want to know which kind of report fits, start with appraisal vs. estimate or call (909) 324-6122. Fees are set by the scope of the assignment and quoted before work begins, and they do not depend on the value.

Sources

• California Revenue and Taxation Code section 51 (lesser of factored base year value or full cash value) (accessed October 30, 2026)
• California Revenue and Taxation Code section 110.1 (base year value) (accessed October 30, 2026)
• California Revenue and Taxation Code section 110 (full cash value) (accessed October 30, 2026)
• California Constitution, Article XIII A, section 2 (accessed October 30, 2026)
• California Revenue and Taxation Code section 2192 (lien date) (accessed October 30, 2026)
• Los Angeles County Office of the Assessor, decline in value (accessed October 30, 2026)
• The Appraisal Foundation, USPAP (accessed October 30, 2026)
• Claremont Heritage, architecture (styles and eras) (accessed October 30, 2026)

Gordon Hall, California Certified Residential Real Estate Appraiser, BREA No. AR003877 (lookup: https://www2.brea.ca.gov/breasearch/faces/party/view.xhtml?id=23601). Reports are prepared in conformity with the Uniform Standards of Professional Appraisal Practice (USPAP). Nothing here is legal or tax advice; admissibility is always the court's decision.