Alameda County's filing period for 2026 regular assessments is open through September 15, 2026. The Clerk requires a $50 nonrefundable processing fee with every application. Online filing is available, but paper filers must use the county's current BOE-305-AH form, complete it in duplicate, provide original signatures, and include the payment. A missing fee or obsolete form can make the filing invalid. The current notice allows in-person filing until 5:00 p.m. on the deadline and treats a U.S. mail postmark by midnight as timely. FairPath can organize a manual owner filing checklist, parcel facts, comparison analysis, and hearing exhibits. It does not submit the application, sign through DocuSign, pay the fee, choose an appeal type, provide an opinion of value, or appear for the owner.
Assessment context: Alameda's 2026 instruction booklet distinguishes a one-year decline-in-value appeal from a challenge to a base-year value created by a purchase or new construction. For Proposition 8 relief, compare fair market value on the January 1, 2026 lien date with the factored base-year ceiling; a temporary reduction does not permanently reset that base. Confirm the parcel, land and improvement values, property characteristics, transfer and permit history, and the exact item selected on the application. The county contains dense Oakland and Berkeley neighborhoods, shoreline and industrial influences, hillside and view properties, established inner-ring suburbs, newer Dublin developments, Tri-Valley markets, condominiums, small multifamily buildings, and agricultural land. City, neighborhood, topography, transit access, view, seismic or condition issues, lot utility, and renovation level can produce large differences within a short radius.
Filing process: Start at the Clerk's official appeals page and use the 2026 notice and current application. Select only one appeal type per application and file each roll year separately. For an online filing, complete the county workflow, use its electronic signature process, pay the fee, and retain the submission receipt. For paper, submit the signed original and duplicate with a $50 check or money order payable to the County of Alameda by mail, courier, or in person at 1221 Oak Street, Suite 536, Oakland. Fax and email are not valid paper-filing substitutes. Attach the underlying notice when appealing a supplemental, escape, or calamity reassessment. Do not confuse application attachments with hearing evidence: the county tells applicants not to attach hearing exhibits to the application and to bring five document copies to the hearing.
Evidence to review: Frame evidence around the correct valuation date and appeal theory. Alameda's current notice states that evidence for a January 1, 2026 decline-in-value appeal cannot rely on comparable sales newer than 90 days after the lien date; it identifies sales before March 30, 2026 as the applicable cutoff. Build a concise grid showing verified sale date and price, parcel, municipality, neighborhood, property type, living area, lot, age, renovations, condition, parking, view, and any adjustment. The booklet says purchase price and similar-property sales are often the best market evidence, while income-producing properties may also require income, expense, and rental comparisons. Use dated photographs, permits, inspection reports, bids, or engineering material for physical-record errors and deferred condition. Alameda can determine the entire property's taxable value, which may be increased or decreased, so present a supported whole-property conclusion rather than isolated lower components.
Current deadline guidance: 2026 regular assessment appeals: July 2 through September 15, 2026. Alameda County's 2026-2027 regular assessment appeal period runs from July 2 through September 15, 2026. A regular application must be received or postmarked by September 15. Supplemental and escape assessment applications are due within 60 days of the notice date, while a calamity reassessment appeal is due within six months of its notice date.
Alameda requires a $50 nonrefundable fee with each appeal and treats an application without timely payment as incomplete and subject to rejection.
Paper filers must use the current county form, submit it in duplicate with original signatures, and cannot substitute fax or email delivery.
The 2026 notice allows only one appeal type per application and requires a separate application for every roll year being challenged.
For a January 1, 2026 decline-in-value case, Alameda says hearing comparables must have sold before March 30, 2026 and asks for five evidence copies at hearing.
Official filing authority: Alameda County Assessment Appeals Board Unit. https://aab.alamedacountyca.gov/
Source: Alameda County Clerk of the Board, 2026-2027 Assessment Appeal Application Notice, https://acgov.org/clerk/forms/NOTICE2026-revised.pdf. Reviewed 2026-07-16.
Source: Alameda County Clerk-Administrator, 2026 Assessment Appeals Board Instruction Booklet, https://acgov.org/clerk/forms/AABBOOK2026_Final-Final.pdf. Reviewed 2026-07-16.
Source: Alameda County Clerk of the Board, Assessment Appeals, https://acgov.org/clerk/assessment.htm. Reviewed 2026-07-16.
Source: County of Alameda, Online Assessment Appeal Application, https://aab.alamedacountyca.gov/. Reviewed 2026-07-16.