Alameda County’s September 15 Assessment-Appeal Window

Alameda County’s regular assessment-appeal filing period runs from July 2 through September 15. That calendar window applies to regular assessments; supplemental, escape, and calamity assessments follow different timing rules.

Official source

Alameda County Assessment Appeals:
https://www.acgov.org/clerk/assessment.htm

Source reviewed August 2, 2026. County forms, fees, and instructions can change. Confirm the live county page and the deadline applicable to the assessment notice before relying on this summary.

Regular and notice-specific timing

The county describes September 15 as the deadline for regular assessment appeals. Its published materials identify separate periods for supplemental and escape assessments and for calamity reassessments. The assessment type on the notice therefore matters as much as the date on the calendar.

A homeowner can preserve the complete notice, identify the parcel number and assessment type, and compare the county’s property description with the property as it exists. That review can reveal questions involving living area, land, age, quality, condition, or listed features.

Application details matter

Alameda County publishes its own current application and instructions. The county’s materials also describe a processing fee and completion requirements. A prior-year form, incomplete submission, or missing required payment may not satisfy the county’s current process.

Before submitting anything, use the live county form and retain a copy of the completed application, supporting material, payment record, and submission confirmation or postmark evidence.

Keep the sources visible

County-record facts, homeowner-provided facts, and analytical comparisons should remain separate. Photographs, estimates, corrections, and other owner-provided material should be labeled and reviewed by the homeowner before entering an evidence packet.

FairPath helps homeowners organize sourced information into a packet they can review and use themselves. The homeowner remains responsible for deciding whether and how to file, submit, and present an appeal. FairPath does not file or communicate with Alameda County on the homeowner’s behalf and does not guarantee a value change, tax savings, acceptance, or another outcome.