Claremont, La Verne and Pomona are assessed by the Los Angeles County Office of the Assessor; Montclair, Upland, Rancho Cucamonga and Chino are assessed by the San Bernardino County Assessor-Recorder-County Clerk. Each county has its own Assessment Appeals Board, its own forms and its own process. An appraisal prepared for a property tax appeal documents the house's condition and the closed sales that best reflect its market value as of the January 1 lien date. The board, not the appraiser, decides what value goes on the roll.
What is a decline-in-value appeal?
A decline-in-value appeal asks the county to enroll the property's market value for a given year because that value has fallen below its factored base year value. California Revenue and Taxation Code section 51 sets the taxable value of real property as the lesser of two numbers: the base year value, compounded each year by the inflation factor the statute sets out, or the full cash value, meaning market value, as of the lien date.
In plain words, the base year value is usually the value set when the house last changed hands or was newly built, stepped up a little each year. If the market value on January 1 is lower than that stepped-up number, the statute says the lower one is the taxable value for that year.
The lien date matters because it fixes the question. Section 2192 of the same code says taxes attach as of 12:01 a.m. on January 1 preceding the fiscal year. An appeal about a given year is about what the house was worth on that January 1, not on the day the bill arrived and not today.
Is the assessed value an appraisal?
No. The assessed value is the county's enrolled value for tax purposes, set by the rules above, and it is not an appraisal. An automated estimate from a website is not an appraisal either, and neither is an agent's comparative market analysis or a cash offer. An appraisal is an independent opinion of market value as of a stated date, developed from closed comparable sales by a licensed appraiser under the Uniform Standards of Professional Appraisal Practice.
The board weighs the Assessor's evidence and the owner's as of the same date. The appraisal is how the owner's opinion of value is documented rather than asserted.
What are the two routes in each county?
Both counties offer an informal step with the Assessor and a formal appeal to a board. They are separate, and one does not replace the other.
Los Angeles County. The Office of the Assessor has a decline-in-value review page that explains how an owner asks the Assessor to review the value. The formal appeal goes to the Los Angeles County Assessment Appeals Board, administered through the Board of Supervisors Executive Office, which describes its role as settling valuation disputes between taxpayers and the Assessor in a quasi-judicial capacity. Applications can be filed through the board's online filing site.
San Bernardino County. The Assessor-Recorder-County Clerk's appeals page encourages the taxpayer to contact the Assessor's office for an informal review first and to provide any information relating to the value of the property. If that does not resolve it, the San Bernardino County Assessment Appeals Board, administered by the Clerk of the Board of Supervisors, hears the case and establishes the value after considering what the owner and the Assessor present.
Filing periods are set by each county and they are not stated here. Confirm the current filing period on the county's page before relying on any date, and file on the county's own forms.
Why does the county line matter on a street like this?
Because two houses built in the same years, to similar plans, can sit a few hundred feet apart and still answer to different assessors, different appeals boards and different public-record conventions.
The line between Claremont and its San Bernardino County neighbors is easy to cross without noticing. Mills Avenue is the western boundary of Montclair. East of the Claremont Colleges, crossing Claremont Boulevard or Mills Avenue, the landscape shifts, and Sixth Street becomes the wider Arrow Route. Postwar ranch houses sit on both sides.
- Comparable sales from across the line are usable evidence of market value. Buyers do not stop at a county boundary. But the report has to explain why the sale was used, how the location differs, and what adjustment, if any, the market supports for that difference.
- Records do not line up neatly. Each county's data reports living area, year built, additions and lot size in its own way. The appraiser measures the subject house and reconciles each comparable's reported details against the listing and permit history rather than copying one county's field into the other county's grid.
For more on how that testing is done, see what the county line does to comparable sales.
What does an assessment appeals hearing expect?
A hearing is an evidence session. The State Board of Equalization's publication on residential appeals says the board bases its decision on the evidence presented by the owner and the Assessor at the hearing, and evaluates the suitability of any approach to value and the data each side used.
The same publication makes several points that shape the appraisal:
- In most residential appeals, sales of similar properties are the most reliable evidence of market value.
- Comparable sales dated more than 90 days after the valuation date cannot be admitted into evidence. Sales before the valuation date are acceptable, and sales closer to it are usually viewed as more reliable.
- Comparability is judged on whether the sale was an arm's-length open market transaction, whether the property is physically similar (distance, zoning, rooms, year built, living area, lot, quality, condition), and whether the sale is relevant to the valuation date.
- The party presenting sales should be ready to discuss the differences and adjust for them.
An appeal appraisal is built around those points: a stated valuation date, sales that meet the timing rule, a written reason for each sale chosen, and adjustments that are shown rather than implied. Who carries the burden of proof depends on the type of appeal and whether the house is an owner-occupied principal residence; the publication explains it, and the board applies it.
What does the appraiser need from you?
The more of this you have, the more precisely the scope of work, the type and extent of research and analysis, can be set before the inspection.
Item | Why it matters |
|---|---|
The assessment notice or tax bill | Shows the county, the roll year and the value being questioned |
The assessor's parcel number | Ties the report to the county's record without ambiguity |
Condition evidence as of January 1 | Photos, inspection reports or repair invoices from around the lien date |
Permits for additions, conversions or an ADU | Confirms what legally existed on the lien date |
Any recent purchase documents | A recent sale of the subject itself is evidence the board will ask about |
Which county's board you are filing with | Sets the format and the forms the report is prepared alongside |
The inspection runs 30 to 60 minutes for a standard single-family home, longer for hillside, custom, multi-family or homes with additions. Turnaround is typically three to five business days from the inspection. The fee is set by the scope of the assignment and quoted before work begins, and the fee does not depend on the value.
What this looks like in practice
These are the kinds of files that come in, described without names, addresses or figures.
- A postwar ranch house just west of Mills Avenue in Claremont, where the nearest similar sales on the lien date closed in Montclair. The report uses them, states the location difference, and pairs them with Claremont sales to test whether the market treated the line as meaningful for that kind of house.
- An Upland house with deferred roof and foundation work on January 1 that was repaired later in the year. The condition analysis relies on dated invoices and photos, and the report states that the condition is valued as it stood on the lien date.
Next step
If your house is in Claremont or elsewhere in Los Angeles County, or in Montclair or elsewhere in San Bernardino County, read how the property tax appeal appraisal is scoped, then order an appraisal with your notice and parcel number in hand, or call (909) 324-6122.
Sources
- California Revenue and Taxation Code section 51 (taxable value is the lesser of factored base year value or full cash value): https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=RTC§ionNum=51 (accessed 2026-09-28)
- California Revenue and Taxation Code section 2192 (lien date): https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=RTC§ionNum=2192 (accessed 2026-09-28)
- Los Angeles County Office of the Assessor, decline in value: https://assessor.lacounty.gov/tax-relief/decline-in-value (accessed 2026-09-28)
- Los Angeles County Assessment Appeals Board: https://bos.lacounty.gov/services/assessment-appeals/ (accessed 2026-09-28)
- Los Angeles County Assessment Appeals Board online filing: https://lacaab.lacounty.gov/Home.aspx (accessed 2026-09-28)
- San Bernardino County Assessor-Recorder-County Clerk: https://arc.sbcounty.gov/ (accessed 2026-09-28)
- San Bernardino County Assessor-Recorder-County Clerk, assessment appeals and informal review: https://arc.sbcounty.gov/assessment-appeals/ (accessed 2026-09-28)
- San Bernardino County Assessment Appeals Board, Clerk of the Board of Supervisors: https://cob.sbcounty.gov/assessment-appeals/ (accessed 2026-09-28)
- California State Board of Equalization, Publication 30, Residential Property Assessment Appeals: https://www.boe.ca.gov/proptaxes/pdf/pub30.pdf (accessed 2026-09-28)
- Montclair, California (Mills Avenue as the western boundary): https://en.wikipedia.org/wiki/Montclair,_California (accessed 2026-09-28)
- The Student Life, city limits on the Los Angeles County line: https://tsl.news/city-limits-on-the-los-angeles-county-line/ (accessed 2026-09-28)
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
Does the appraisal have to be as of January 1?
For a decline-in-value appeal, yes. The valuation date is the January 1 lien date of the year under appeal, and the comparable sales have to satisfy the timing rule described above.
Can a Montclair sale be used for a Claremont house?
Yes, if it is a genuine comparable and the report explains the location difference. What a board will question is a cross-line sale used without any explanation.
Do I have to use an appraiser to appeal?
No. Owners can present their own evidence. An appraisal is one way to document market value in a form the board is used to reading.
Will you tell me what value to expect before the appraisal?
No. The value is developed from the sales after the inspection, and no outcome is discussed beforehand. The board decides what goes on the roll.