County filing guide
How to appeal your property tax in Alameda County
Regular decline-in-value appeals. Supplemental and escape assessments have different deadlines.
Filing options
A filing-fee waiver may be available. Check with the county to see whether you qualify.
Filing instructions
Informal review
Find the decline-in-value review entry point.
Alameda informal — Find the decline-in-value / informal review entry point. Select E-form to submit the informal review online.
Alameda informal — Select the way you want to submit the informal review. We recommend submit E-form for convenience. Enter your parcel number or property address to continue.
Alameda informal — Enter your parcel number or provide address to proceed. Select your property from the search results.
Alameda informal — Your address will show up on the bottom. Click it to proceed Enter the owner’s first and last name to continue.
Alameda informal — Type in owner first name and last name to proceed. Alameda asks for two comparable sales. Use the two best supporting sales from your PropertyHero report.
Alameda informal — Alameda asks for 2 comparable market data information. Grab the 2 comps from the generated report from PropertyHero to fill out the 2 comps
If the portal fails or you have any question: call the assessor’s office at 510-272-3787.
The formal appeal window for 2026-27 has closed. The deadline was September 15, 2026. These instructions remain available as a reference.
Formal appeal online
Open the Alameda County assessment appeal portal. Choose Create an Account, or enter your email and PIN and click Log In if you already have an account.
Alameda formal appeal — step 1 For a new account, enter and confirm your email, fill in your name and applicable contact details, select No for “Are you an agent?” if filing for yourself, and click Create Account.
Alameda account registration: contact details, owner selection, and Create Account. Follow the account instructions, then return to the login page and sign in with your email and PIN. Use Forgot your PIN? if you need it emailed to you.
Begin a new assessment appeal in your account. Use a separate application for each parcel and assessment year.
Enter the applicant’s name, mailing address, and contact details, then identify the property using its parcel number and address from the assessment notice or tax bill.
Enter the assessed values and your opinion of value in the applicable categories. For a regular decline-in-value appeal, use the property’s market value as of January 1 of the year being appealed.
Select Regular Assessment and Decline in Value for an annual market-value dispute. Complete the remaining questions using the county’s application instructions, including written findings and claim-for-refund choices.
Provide any required authorization or notice documents. Keep hearing evidence for the hearing; the application instructions say not to attach it to the application.
Review all entries, correct missing information, and follow the portal’s DocuSign, electronic-submission, and $50 processing-fee prompts to complete filing. If seeking a fee waiver, use the county’s request form and confirm submission instructions with the Clerk at 510-272-3854.
Keep copies of the submitted application, signed documents, payment receipt, and any confirmation provided. Return to the portal to view submitted appeals and respond to Clerk requests.
After you file
Informal review
Keep your request confirmation and any correspondence from the Assessor. Check the formal appeal deadline above when considering a separate appeal.
Formal appeal
Keep a copy of your application and filing confirmation. Watch for notices from the Clerk of the Board and follow the county’s instructions for any hearing.
Open my appeal plans →Contacts & sources
Clerk of the Board
Runs the formal appeal
510-272-3854 · appeals page ↗
1221 Oak Street, Suite 536, Oakland, CA 94612
This guide covers the regular decline-in-value appeal; supplemental or escape assessment notices follow different deadlines. Every date and fee here was checked against official sources, listed below with the date checked. If the county's page ever differs from this guide, follow the county's page.
Sources
Informal sources
- Assessor’s decrease-your-assessment page — existing guide’s source for the informal review window and no-fee process (dataset check July 11, 2026).
- Assessor’s decline-in-market-value page — existing value-notice reference (dataset check July 11, 2026; the recorded quote concerns 2025).
- Scope: the existing informal walkthrough and screenshots were retained. They were not rechecked as part of this formal-guide update.
Informal review
- https://www.acassessor.org/homeowners/decrease-your-assessment/ · “Informal reviews are available July 1 through December 31 each year” (checked September 7, 2026)
- https://www.acassessor.org/homeowners/decrease-your-assessment/ · “There is no fee to request an informal review” (checked September 7, 2026)
Formal sources
- This formal walkthrough covers a homeowner’s regular decline-in-value appeal. Supplemental, escape, and other assessment notices have different deadlines. Follow the county’s current instructions if they differ from this guide.
- Clerk’s assessment appeals page — official portal, current application documents, fee-waiver form, and contact number.
- Appeal portal and registration page — login uses email and PIN; public account fields and actions shown in the screenshots.
- 2026–27 filing notice — standard July 2–September 15 filing period, $50 nonrefundable fee, and electronic signatures through DocuSign.
- June 2026 instruction booklet, printed pages 7–8 — expressly permits online application submission, DocuSign, and fee payment. Other passages still describe paper filing; the specific online-filing instructions are the basis for this walkthrough.
- Deadline exception: the booklet states that someone who did not receive an assessed-value notice before August 1 may file by November 30. Confirm applicability with the Clerk; portal access by itself does not establish eligibility for a late regular appeal.
- Application and instructions — applicant/property details, values, assessment type, reason, remaining choices, and hearing-evidence instructions.
- Fee-waiver request — eligibility and supporting information. An online waiver-submission path was not verified.
- Verification scope: official sources checked September 29, 2026. Public login and registration screens were inspected and captured; no account was created, fee paid, or appeal submitted. Steps after login summarize county documents, not observed account screens. The precise sequence, button labels, payment methods, and confirmation format behind sign-in were not verified.
Formal appeal window
- https://www.boe.ca.gov/proptaxes/pdf/lta26023.pdf · “The regular appeals filing period in each county will begin on July 2, 2026, and will end on September 15, 2026, for those counties where the Assessor mails assessment notices to all taxpayers with property on the secured roll by August 1, 2026. For counties where assessment notices are not mailed by August 1, 2026, the filing period is extended to November 30, 2026.” (checked July 10, 2026)
Filing fee
- https://www.acgov.org/clerk/forms/NOTICE2026-revised.pdf · “A non-refundable application Processing Fee of $50 per application must be paid at the time of filing the application.” (checked July 11, 2026)
- https://www.acgov.org/clerk/assessment.htm · “Request to Waive Nonrefundable $50 per Parcel Assessment Appeal Application Processing Fee” (checked July 11, 2026)
Filing address
- https://www.acgov.org/clerk/forms/NOTICE2026-revised.pdf · “Please mail your application to: County of Alameda, Assessment Appeals Board 1221 Oak Street, Suite 536, Oakland, CA 94612.” (checked July 11, 2026)
Filing channels
- https://www.acgov.org/clerk/forms/NOTICE2026-revised.pdf · “Alameda County now offers an online application process for assessment appeals applications.” (checked July 11, 2026)
- https://www.acgov.org/clerk/forms/NOTICE2026-revised.pdf · “If you file by mail, your application must be postmarked by midnight on the last day of the filing period.” (checked August 3, 2026)
- https://www.acgov.org/clerk/forms/NOTICE2026-revised.pdf · “Applications may be filed in person until 5:00 p.m. on the last day of the filing period, at 1221 Oak Street, Ste. 536, Oakland, CA 94612.” (checked August 3, 2026)
Fee waiver
- https://www.acgov.org/clerk/assessment.htm · “Request to Waive Nonrefundable $50 per Parcel Assessment Appeal Application Processing Fee” (checked July 11, 2026)
Common questions about appealing in Alameda County
When is the deadline to appeal in Alameda County?
The 2026-27 filing period for a formal appeal in Alameda County ran from July 2 to September 15, 2026, so it has closed for this tax year.
The Assessor takes informal review requests from July 1 to December 31, 2026.
What does it cost to file an appeal in Alameda County?
The county filing fee for a formal appeal is $50.
There is no fee for the Assessor's informal review.
A filing-fee waiver may be available. Check with the county to see whether you qualify.
Informal review or formal appeal: which one first?
Alameda County offers both: an informal review with the Assessor, and a formal appeal filed with the Clerk of the Board (due September 15, 2026).
The state's own guidance says to talk to the Assessor's office first: if their staff finds an error, they can lower the roll directly and you may never need to file. Missing an informal review costs you nothing; missing the formal deadline costs you the year.
Which form do I file, and where?
The formal appeal uses the state's application form, BOE-305-AH ↗.
Alameda County accepts the formal appeal online, by mail, or in person. File online through the county's appeals portal ↗.
Mail it to the Clerk of the Board at 1221 Oak Street, Suite 536, Oakland, CA 94612.
Check the Clerk of the Board's appeals page ↗ or call 510-272-3854 before you file.
How long does an appeal take?
You get written notice at least 45 days ahead, hearings are open to the public (you can watch one first), and boards are expected to decide within two years of filing. You can still settle at any point before your date.
Do homeowners actually get their assessments lowered?
7,936 homes in Alameda County had temporarily reduced assessments in tax year 2025-26.