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Contra Costa County · CaliforniaAppeal Your Contra Costa County Property Tax.
The Contra Costa County Assessor's office in Martinez values every property on California's January 1 lien date. When that assessed value overshoots the market, file both: an informal Prop 8 decline in value review with the assessor (fast, often resolves without a hearing) and a formal Assessment Appeals Board filing with the Clerk of the Board (protects your right to a hearing).
Contra Costa County Assessor
Source: California State Board of Equalization county directory.
Where to File in Contra Costa County
Deadline verified against the California BOE county assessment appeals filing periods list. Always confirm current-year details with the Contra Costa County Clerk of the Board before filing.
Contra Costa County Prop 8 Filing Steps
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Check if your property qualifies
Run your address or APN through vulorean.com. If your assessed value exceeds current market value as of January 1, you have a viable Prop 8 claim.
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Get your Vulorean valuation report
A market value opinion as of January 1 with comparable sales. Choose DIY or Concierge.
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Submit your appeal
File both: an informal review with the Assessor and a formal appeal with the Assessment Appeals Board.
DIY Fill out the informal Request for Value Review and the formal Assessment Appeal Application using your Vulorean report.Concierge Your rep prepares both forms and files them on your behalf.- Informal form: Download Request for Value Review — Residential (PDF) (included with your report - purchase to access)
- Formal appeal form: Download Assessment Appeals Application (PDF) (included with your report - purchase to access)
- Property tax reappraisal landing page: contracosta.ca.gov — Assessment Appeals
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File your appeal
Submit the formal appeal to the Contra Costa County Assessment Appeals Board.
DIY Mail to 1025 Escobar Street, 1st Floor, Martinez, CA 94553.Concierge Your rep submits the appeal on your behalf. -
Await response
If approved, you will be notified. If a hearing is scheduled, you may need to attend.
DIY Watch for a response by mail. Attend any scheduled hearing or send a representative.Concierge Your rep monitors the response and handles any hearing.
Contra Costa County reminder: California's Prop 13 caps annual taxable value growth at 2%, so a successful appeal keeps paying dividends every year your market value sits below the Prop 13 base. Prop 8 is the complement. It lets you capture temporary market dips. Both paths run through the Contra Costa County Assessor in Martinez.
When You Probably Qualify for a Contra Costa County Reduction
- Your current assessed value is above recent sales of comparable homes in Contra Costa County
- You bought in Contra Costa County in the last 12 months below the county's assessed value
- Your Contra Costa Assessor parcel record has errors, wrong square footage, added features that don't exist, or incorrect grade
- Your home has unrepaired damage, structural issues, foundation settling, or major deferred maintenance
- Your neighborhood's market softened but the Contra Costa Assessor hasn't adjusted
Contra Costa County Appeal Package · $55 Flat
We pull your Contra Costa County Assessor record, build comparable sales, and produce a filing ready BOE-305-AH appeal in 48 hours. You keep 100% of the savings.
Start My Contra Costa County Appeal →Contra Costa County Property Tax FAQ
When does Contra Costa County mail assessment notices?
California counties, including Contra Costa, typically mail notices in June or July. Your window to file BOE-305-AH opens July 2 and closes November 30 in Contra Costa County, per the California BOE county filing periods list. Confirm current-year dates with the Contra Costa Clerk's office.
Do I have to use an attorney?
No. The California Assessment Appeals Board is designed for pro se homeowners. Filing BOE-305-AH is a two page form and hearings are informal. Most Contra Costa County homeowners file and represent themselves.
Will my Contra Costa County taxes go up if I appeal?
No. California appeal outcomes at the Assessment Appeals Board are strictly reductions or no change. Prop 13 caps assessed value growth at 2% per year regardless.
Is Prop 8 the same as Prop 13?
No. Prop 13 is the base year rule that caps annual assessment growth. Prop 8 is the companion rule that lets the assessor (or you) temporarily drop your value below the Prop 13 base when the market falls. When the market recovers, your value can rise back up to the Prop 13 cap, but not above it.