Property Tax Appeal Appraisals for California Commercial Property

What is a Prop 8 decline in value?

Under Proposition 13, a property's assessed value is generally set when it changes ownership or is newly constructed, then rises by no more than 2 percent a year. That adjusted number is the factored base year value. Proposition 8 (1978), codified in Revenue and Taxation Code Section 51, adds a second test. For each lien date, the taxable value is the lesser of the factored base year value and the property's full cash value (market value) as of the lien date, January 1.

As the State Board of Equalization explains, a property only benefits when its market value falls below its factored base year value. Once a property is reduced, the assessor must reappraise it every year until its market value is above the factored base year value again. While it is in decline-in-value status, the assessment can rise by more than 2 percent in a year, but never above the factored base year value.

For commercial property, a decline usually comes from something you can document: tenants that left, rents that dropped, rising vacancy or expenses, a change in the neighborhood, or physical problems with the building. A properly supported appraisal ties those facts to a market value on January 1.

When is the 2026 assessment appeal deadline in my county?

The regular filing period for 2026 began July 2, 2026. Under Section 1603, it ends September 15 in counties where the assessor mailed assessment notices to all secured roll taxpayers by August 1, and November 30 everywhere else. The BOE's 2026 county filing period list (Letter To Assessors No. 2026/023) shows:

November 30, 2026 in most counties, including Los Angeles, Orange, San Diego, Riverside, San Bernardino, Sacramento, Fresno, Kern, Contra Costa, San Mateo, Santa Barbara, Sonoma, Napa, Monterey, Santa Cruz, San Joaquin, Stanislaus, Tulare, Imperial, Solano and Marin.

September 15, 2026 (already passed for this year's regular period) in Alameda, Alpine, Inyo, Kings, Mono, Placer, San Francisco, San Luis Obispo, Santa Clara, Sierra and Ventura.

Section 1603 also has narrow exceptions, for example when a taxpayer did not receive the assessment notice at least 15 days before the deadline. Different filing deadlines apply to supplemental, escape and other assessments made outside the regular assessment period, generally 60 days from the notice or tax bill under Section 1605. Always confirm the deadline, the current form (BOE-305-AH, Assessment Appeal Application) and any filing fee with the clerk of the board in the county where the property is located. If your county's deadline is November 30, an appraisal takes time to scope and write, so call (805) 990-9700 now.

Why does a commercial tax appeal need a real appraisal?

Because in most commercial appeals, the burden is on you. According to the BOE's assessment appeal FAQ, the assessor carries the burden of proof only in listed situations, such as an owner-occupied single-family home. In all other situations, the applicant must prove the property was not correctly assessed and presents evidence first.

The appeals board decides fair market value from the evidence presented at the hearing, and it is not bound by either side's number. It can lower the value, leave it alone or raise it. Information you gave the assessor earlier does not count unless you present it at the hearing. The BOE notes that a formal appraisal is allowed as evidence, and that the board may require the person who prepared it to be present to answer questions.

The Revenue and Taxation Code says the same thing in its own words: under Section 1610.8, the applicant "shall establish the full value of the property by independent evidence." There is also a timing rule that matters for appraisers. The value is as of January 1, and the BOE says an appeals board may not consider comparable sales that occurred more than 90 days after that date. So a 2026 appeal appraisal is a retrospective appraisal: market data, rents and conditions as of January 1, 2026, and the property described as it was then.

Should I start with the assessor or file an appeal?

Often both. The BOE suggests contacting the county assessor first. Most assessors will review a property for a decline in value on request, sometimes with a short informal review form, and they may agree with well-supported evidence. If you still disagree, you file an assessment appeal with the clerk of the board during the filing period. The filing window does not wait for an informal review, so ask your tax advisor whether to file the application before the deadline while a review is still pending.

A few other rules from the BOE are worth knowing. Keep paying your property taxes while the appeal is pending, or penalties and interest apply; if you win a reduction, you receive a refund with interest. Either side can request an exchange of information before the hearing, with the requesting party's opinion of value and supporting data at least 30 days before the hearing and the response at least 15 days before. If the assessed value is more than $100,000, the assessor may request one from you. The law allows up to two years for an application to be resolved, and a challenge to the board's decision goes to superior court within six months of the decision.

If the property was damaged in a fire, flood or other disaster, ask the assessor about calamity reassessment as well, which follows its own rules.

How do owners, CPAs and tax consultants work with us on an appeal?

Call or text (805) 990-9700 and you talk directly to the appraiser, not a coordinator. Tell us the property, the county, the roll year and lien date, the current assessed value, whether an application is filed or a hearing is set, and your deadlines. Useful documents include the assessment notice or tax bill, rent rolls and leases as of January 1, operating statements for the prior year and the year before, vacancy and leasing history, any purchase contract or recent offers, and repair estimates or reports on the property's condition.

Rush commercial appraisals are available in 5 to 7 business days. Standard timing depends on the property and scope. Call (805) 990-9700 for a timeline on your assignment. Our appraisals are independent: we never take an assignment that requires a predetermined value, we cannot promise any reduction, and our fees are never tied to the value or the outcome.

Tax appeal work is one of many kinds of commercial appraisal we write. We appraise every commercial property type for lending, estate and trust, date of death, divorce, litigation, partition, eminent domain, fractional interest and more. See commercial appraisals and the property types we appraise.

This page is general information, not legal or tax advice. Talk to your attorney, CPA or property tax advisor about your appeal.

Talk to your appraiser: (805) 990-9700