How to Appeal Your Property Tax in Alameda County
Filing an appeal sounds intimidating, but it's simpler than you think. Here's how the two-track system works in Alameda County.
What are the two ways to appeal my property tax?
Alameda County offers two paths: a free informal review through the Assessor's office, or a formal appeal through the Assessment Appeals Board with a $50 filing fee. Most people start with the informal review — it's free, faster, and doesn't require a hearing.
What is an informal review?
Through the Alameda County Assessor's Office
You submit your evidence — comparable sales showing your home is overassessed — directly to the Alameda County Assessor's Office. A certified appraiser reviews it and makes a determination.
- Free to file — no fee
- No hearing required — a certified appraiser reviews your evidence
- Typically faster than the formal process
- If the assessor agrees, they adjust your assessed value — and your taxes go down
Submit your informal review request early
For the best chance of having your review completed before the formal appeal window opens, submit your request to the Assessor's office by April 10. There's no hard deadline for informal requests, but earlier is better — the Assessor needs time to review your evidence before values are finalized in June.
What is a formal property tax appeal?
Through the Assessment Appeals Board
You file an Application for Changed Assessment (BOE-305-AH) with the Assessment Appeals Board. This is a more structured process — you may be scheduled for a hearing where you present your evidence, and the board makes an independent determination.
This is the route if the informal review doesn't result in a satisfactory adjustment, or if you prefer a formal process from the start.
- Filing window: July 2 – September 15 each year. If September 15 falls on a weekend or holiday, the deadline extends to the next business day.
- $50 filing fee
- You may be scheduled for a hearing to present your case
- The board makes an independent determination of your property's value
Which should you choose? Most homeowners start with the informal review. It's free, faster, and doesn't require showing up to a hearing. If the result isn't what you hoped for, you can still file a formal appeal.
What evidence do I need for a property tax appeal?
You need comparable sales — recent sales of homes similar to yours that sold for less than your assessed value. This is the foundation of any property tax appeal. The stronger your comps, the stronger your case.
“Similar” means comparable in:
- Square footage and lot size
- Bedrooms and bathrooms
- Condition and age
- Proximity to your home
Why adjustments matter
If a comp is smaller or has fewer bedrooms than your home, the assessor will adjust the sale price upward to account for the difference. You want comps that are genuinely comparable after adjustments — not just homes that sold for less.
This is what Overassessed does. We find comparable sales from county records, calculate professional-grade adjustments for differences in size, features, and condition, and package the evidence you need — ready to submit.
Your assessed value might be higher than market value for several reasons explained under Proposition 8 — including assessment creep, market corrections, and neighborhood changes.
The Overassessed Filing Guide includes comparable sales data, dollar adjustments, and a ready-to-submit value argument — everything listed above.
See what's included →How do I file an informal property tax review step by step?
Here's what the process looks like from start to finish. It takes about 10 minutes of active work on your end — the rest is waiting.
Check if you qualify
Compare your assessed value to your home's estimated market value. If comparable homes are selling for less than your assessed value, you likely have a case.
Overassessed does this for you — enter your address and we'll pull your assessment and run the comparison.
Gather comparable sales evidence
You need recent sales of similar homes near yours that sold for less than your assessed value. The comps should be adjusted for differences in size, bedrooms, condition, and other features.
The Overassessed Filing Guide includes selected comps with professional-grade adjustments, ready to submit.
Submit your request to the Alameda County Assessor's Office
Send your evidence to the Alameda County Assessor's Office. You can submit online through their website, by mail, or in person. Include your parcel number, your assessment details, and your comparable sales evidence.
Wait for the appraiser's review
A certified appraiser at the Assessor's office will review your submission and evaluate your evidence against their own analysis. This typically takes a few weeks to a couple of months.
Receive your determination
If the appraiser agrees your property is overassessed, they'll adjust your assessed value. The tax savings will show up on your next property tax bill. If they disagree, you can still file a formal appeal with the Assessment Appeals Board.
Our Filing Guide gives you copy-paste values for every field on the county form, plus a deadline tracker.
Check if you qualify →Frequently asked questions about property tax appeals
Do I need a lawyer or tax consultant?
No. The informal review process is designed for homeowners to handle themselves — no legal training required. Overassessed gives you the same kind of comparable sales evidence a professional would prepare, packaged and ready to submit.
What if my appeal is denied?
If the informal review doesn't go your way, you can still file a formal appeal with the Assessment Appeals Board. And you can always try again next year — your property is reassessed annually, and market conditions change.
Will filing an appeal raise my assessment?
Not with an informal request — the Assessor can only reduce or confirm your current value, so there's no downside risk. If you later file a formal appeal with the Assessment Appeals Board, the Board does have the legal authority to raise your assessed value based on the evidence at the hearing — though this is uncommon in Prop 8 decline-in-value cases. That's why filing with strong, well-adjusted comparable sales matters, and it's exactly what Overassessed is designed to help you build. California's Prop 13 also limits any increase to your original factored base year value ceiling, so the risk is bounded.
How much could I save?
It depends on the gap between your assessed value and market value. The average Alameda County homeowner who qualifies saves around $1,500/year. Your actual savings depend on your specific property and local comps.
How long does it take?
The informal review typically takes a few weeks to a couple of months from submission to determination. The formal appeal process can take longer, depending on the Assessment Appeals Board's schedule.
Ready to see if you qualify?
Enter your address and we'll compare your assessed value to comparable sales. It takes about 60 seconds.
Overassessed provides estimates based on publicly available data and AI-generated analysis. This is not a formal appraisal, legal advice, or tax advice. Results are not guaranteed, and appeal outcomes depend on county review. Users file their own appeals. AI-generated estimates may differ from actual market values.