How to Appeal a Property Tax Assessment in California

First, know what you're actually appealing

You're appealing the assessed value, not the tax rate. In California, your assessment is generally the lower of your Proposition 13 factored base-year value or the property's market value on the January 1 lien date. If the market value on that date was lower than the value the assessor enrolled, you may be entitled to a reduction.

Step 1: Request an informal decline-in-value (Prop 8) review

If your home's market value has dropped below its factored base-year value, ask your county assessor for a Proposition 8 decline-in-value review. Most counties have a simple online form and a window (often in the spring and summer) to request one. If the assessor agrees, they temporarily lower your assessed value for that year — no hearing required. It can rise again in later years as the market recovers, up to your normal Prop 13 value.

Learn how these temporary reductions work on our Proposition 8 explainer. An informal review is easy, but it doesn't by itself preserve your formal appeal rights — so watch the appeal deadline below.

Step 2: File a formal assessment appeal

To formally contest the value, file an Application for Changed Assessment with your county's assessment appeals board (or board of equalization). There's usually little or no filing fee. Miss the deadline and you generally have to wait until next year, so this is the step where timing matters most.

Which regular period applies depends on whether your assessor mails a value notice to every owner by August 1 (Revenue and Taxation Code §1603). Each county clerk certifies its period to the Board of Equalization every June; for 2026 the 58 counties split like this:

Source: California State Board of Equalization, Letter To Assessors No. 2026/023, County Assessment Appeals Filing Period for 2026 (boe.ca.gov), checked 2026-10-14. Every period opens July 2. When September 15 or November 30 falls on a weekend or holiday the period runs to the next business day. The county clerk of the board, not the assessor, receives the application; the board's own site has the form and any filing fee.

Step 3: Build evidence that actually wins

Appeals are won on comparable sales, not on how you feel about your bill. Assemble:

• Three to six comparable sales in your neighborhood that closed near the January 1 lien date.
• Adjustments for real differences (size, condition, lot, upgrades) between the comps and your home.
• Photos and estimates documenting condition problems, deferred maintenance, or damage.
• Any listing or appraisal showing a market value below your assessed value.

Anchor everything to the January 1 lien date. A sale six weeks before or after January 1 is far more persuasive than one from the prior spring.

Step 4: The hearing and burden of proof

If the assessor doesn't resolve your application beforehand, you present your case to the appeals board. Generally the applicant carries the burden of proving the value is wrong — but for an owner-occupied single-family home, California law shifts that burden to the assessor. Either way, come with clean, dated comparable-sales evidence. The board's decision is binding on the value, though you retain further legal options.

What you can't appeal

• The tax rate itself (it's set by law and voter-approved debt).
• That your taxes simply went up, or feel too high.
• Mello-Roos, parcel taxes, or special assessments (those have their own separate processes).
• Your neighbor's lower assessment — Proposition 13 ties value to each owner's acquisition, so lower neighboring bills are normal.

Assessment appeals by county, FY 2024-25

You are far from alone: California property owners filed 72,064 assessment appeals in FY 2024-25, +4.1% on the 69,219 filed in FY 2023-24, led by Los Angeles (17,600), San Francisco (8,903) and Santa Clara (7,431). About 41% of appeals statewide are residential; the rest are commercial, industrial and other property, which is why business-heavy counties file more appeals per home than suburban ones. Among counties with at least 500 appeals, Sonoma saw the biggest jump (+63%) and Ventura the biggest drop (-43%). Sort the table by any column or type your county's name.

Source: California State Board of Equalization — assessors' workload tables (decline-in-value, calamity, assessment appeals), assessment appeals filed by county and property type (BOE Table K), as reported by each county's clerk of the board. “Filed” counts applications in the fiscal year; residential plus commercial does not sum to the total because other property types (vacant land, agricultural, personal property) are not broken out. Counties that reported no appeals, or did not report, are not listed; Alpine, Lassen, Marin, Plumas and Santa Barbara show the prior year on their county pages.

How appeals turn out

Of the 59,285 appeals resolved statewide in 2024:

So about 34% of resolved appeals ended with a lower value, and the great majority of those never reached a hearing — the assessor's staff reviewed the evidence and stipulated. Of the appeals that did go to a hearing, the board lowered the value in 76% of cases. The large “withdrawn or denied” group is mostly applications abandoned by the owner, filed late or without evidence, or made moot by a Prop 8 reduction the assessor granted on their own.

Source: California State Board of Equalization — assessors' workload tables (decline-in-value, calamity, assessment appeals), assessment appeals activity (BOE Table L), statewide for 2024. A stipulation or reduction elsewhere does not predict your result.

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