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 sourceAlameda County Assessment Appeals:https://www.acgov.org/clerk/assessment.htmSource 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 timingThe 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.

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