An appraiser and an assessor both put a value on a house, but they do different jobs and produce different numbers. The county assessor sets assessed value, the value on the property tax roll, which under California Revenue and Taxation Code section 51 is the lesser of the factored base year value and the full cash value on the January 1 lien date. An independent appraiser, licensed by the Bureau of Real Estate Appraisers, develops an opinion of market value for one property, for a named client and a stated use, as of an effective date the assignment sets. In Claremont, La Verne and Pomona the assessor is the Los Angeles County Office of the Assessor; in Upland, Montclair, Rancho Cucamonga and Chino it is the San Bernardino County Assessor-Recorder-County Clerk.
A county assessment is not an appraisal, and an appraisal does not set anyone's tax. Below: each job, what changes at the Claremont-Upland county line, and where the two meet.
Two jobs side by side
County assessorIndependent appraiser
Purpose
Keep the property tax roll for every parcel in the county
Answer one client's value question for one property
The number
Assessed (taxable) value
An opinion of market value
Rules
California Revenue and Taxation Code
USPAP, with a signed certification
Credential
County staff valuing property for tax hold a State Board of Equalization certificate (section 670)
A license from the Bureau of Real Estate Appraisers
Date
The January 1 lien date (section 2192)
The effective date the assignment sets
Sees the inside
No
Yes, in most assignments
Who decides what it means
The county, and its appeals board in a dispute
The client and intended users: a lender, court, trustee, CPA or board
What the assessor does
The assessor's job is the roll. Under section 110.1, a property's base year value, the full cash value fixed at a purchase, new construction or change in ownership (or as of the 1975 lien date for property held since then), becomes the starting point. Each year it is compounded by an inflation factor under section 51. Full cash value, the tax code's term for fair market value, is defined in section 110 as the amount of cash or its equivalent a property would bring if exposed for sale in the open market, with neither buyer nor seller able to take advantage of the exigencies of the other.
Section 51 then enrolls the lesser of the two: the factored base year value or the full cash value on the lien date. When full cash value falls below the factored base, the lower figure is enrolled, and subdivision (e) has the property reappraised at full cash value each lien date until that value again exceeds the factored base. That is why a house bought long ago in the Euclid Avenue District or near the Claremont Village can carry an assessed value with little relation to recent sales; the roll is working as designed. The county-by-county detail is in why assessed value in Los Angeles County is not market value.
What the appraiser does
An appraiser answers one question for one client. The engagement first sets the intended use, what the report will be used for; the intended users, the people entitled to rely on it; the effective date, the date the opinion of value applies to; and the scope of work, the type and extent of research and analysis. Then comes the inspection, typically 30 to 60 minutes for a standard single-family home, longer for hillside, custom, multi-family or homes with additions, followed by the comparable research, the adjustments and a written report.
The appraiser is independent of every party, including the one who pays, and the fee is set by the scope of the assignment and quoted before work begins; it does not depend on the value. The appraiser does not change the roll. What happens to the report depends on who reads it, explained in what appraised value is and who it is written for.
Two assessors, one line: Claremont and Upland
The Los Angeles and San Bernardino county line runs just east of the Claremont Colleges. Cross Claremont Boulevard or Mills Avenue and you are in Upland or Montclair. Both counties apply the same state law, section 51 included, so the rule for assessed value does not change at the line. What changes is everything around it:
- The office. Claremont, La Verne and Pomona are assessed by the Los Angeles County Office of the Assessor. Upland, Montclair, Rancho Cucamonga and Chino are assessed by the San Bernardino County Assessor-Recorder-County Clerk.
- The review route. Los Angeles County publishes a decline-in-value review. San Bernardino County encourages an informal review before a formal appeal.
- The appeals board. Formal appeals go to the Los Angeles County Assessment Appeals Board on one side and the San Bernardino County Assessment Appeals Board, through the Clerk of the Board of Supervisors, on the other. Filing periods are set by each county; confirm the current period on its own page before filing.
Upland adds a wrinkle of its own. San Antonio Heights, above the city, is unincorporated county land: the San Bernardino County assessor applies there, while city rules do not. A horse-keeping lot there and a tract house south of the 210 sit on the same county roll but in very different markets. More on this in assessed value on both sides of the county line, and the Upland area page describes its pockets.
Where the two jobs meet: a review or an appeal
The jobs meet when an owner believes the full cash value on the lien date is below the enrolled value. An appraisal made as of January 1 can be evidence in a decline-in-value review, an informal review or a formal appeal. The assessor or the appeals board decides what weight it gets; an appraisal does not decide the outcome, and no appraiser can say in advance what a county will do. For a west Upland house, the appraisal uses Upland sales first and explains any Claremont sale it relies on; for a Claremont house, Claremont sales first. Property tax appeals on the county line walks through the process, and the property tax appeal appraisal page describes the assignment. Nothing here is legal or tax advice.
The numbers that are neither
An automated estimate, a statistical estimate an algorithm produces from records and nearby sales, is not an appraisal. A comparative market analysis (CMA), an agent's opinion of likely list or sale price, is not an appraisal. A cash offer, one buyer's price on its own terms, is not an appraisal. The appraisal vs. estimate page sorts them out, and the four different numbers guide puts every one in a single table.
Next step
If you need an opinion of market value for a review, an appeal or any other purpose on either side of the county line, request an appraisal or call (909) 324-6122. Reports are typically delivered three to five business days from the inspection. Every article on value vocabulary is in the value types knowledge center.
Sources
- California Revenue and Taxation Code section 51 (taxable value; annual reappraisal after a reduction): https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=RTC§ionNum=51 (accessed October 30, 2026)
- California Revenue and Taxation Code section 110 (full cash value): https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=RTC§ionNum=110 (accessed October 30, 2026)
- California Revenue and Taxation Code section 110.1 (base year value): https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=RTC§ionNum=110.1 (accessed October 30, 2026)
- California Revenue and Taxation Code section 670 (certificate for property tax appraisal staff): https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=RTC§ionNum=670 (accessed October 30, 2026)
- California Revenue and Taxation Code section 2192 (January 1 lien date): https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=RTC§ionNum=2192 (accessed October 30, 2026)
- Los Angeles County Office of the Assessor, Decline-in-Value review: https://assessor.lacounty.gov/tax-relief/decline-in-value (accessed October 30, 2026)
- Los Angeles County Assessment Appeals Board: https://bos.lacounty.gov/services/assessment-appeals/ (accessed October 30, 2026)
- San Bernardino County Assessor-Recorder-County Clerk, assessment appeals and informal reviews: https://arc.sbcounty.gov/assessment-appeals/ (accessed October 30, 2026)
- San Bernardino County Clerk of the Board, Assessment Appeals: https://cob.sbcounty.gov/assessment-appeals/ (accessed October 30, 2026)
- California Bureau of Real Estate Appraisers, license lookup: https://www2.brea.ca.gov/breasearch/faces/party/view.xhtml?id=23601 (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.
Frequently asked questions
Is the county assessor's value an appraisal?
No. A county assessment is the taxable value on the property tax roll, which under California Revenue and Taxation Code section 51 is the lesser of the factored base year value and the full cash value on the January 1 lien date. It is not an appraisal, which is a licensed appraiser's opinion of market value for a named client and use.
Who assesses property in Claremont and in Upland?
Claremont, La Verne and Pomona are assessed by the Los Angeles County Office of the Assessor, with formal appeals to the Los Angeles County Assessment Appeals Board. Upland, Montclair, Rancho Cucamonga and Chino are assessed by the San Bernardino County Assessor-Recorder-County Clerk, with formal appeals to the San Bernardino County Assessment Appeals Board through the Clerk of the Board of Supervisors.
Can an independent appraisal change my assessed value?
An appraisal made as of the January 1 lien date can be submitted as evidence in a county review or a formal appeal, but the assessor or the appeals board decides what weight it gets and whether the roll changes. No appraiser can say in advance what a county will decide. Filing periods are set by each county; confirm the current period on the county's own page.
Does the county line change how a house is assessed?
The rule does not change: both counties apply the same state law, including Revenue and Taxation Code section 51. What changes is the office that keeps the roll, its review process and the appeals board that hears disputes. Buyers may also weigh the two sides differently, which matters when an appraiser chooses comparable sales.
