Why Overassessed exists.
California homeowners overpay between $1,000 and $3,000 a year in property taxes — not because they have to, but because the right to challenge an overassessment is buried in paperwork most people never see. Overassessed does the hard part: we build the evidence and hand you a guide you file yourself.
Stuart Altman
Founder, Overassessed
Reviewed July 2026
I am not a CPA, an attorney, or a licensed property tax consultant. After months of working through how California's property tax appeal process actually works — and appealing my own home — I've come to believe that matters less than it sounds. The rules are public and written down, the evidence is comparable sales, and the rest is doing the work carefully.
I built this site after I appealed my own property taxes — and won. Last year I started getting letters from companies offering to lower my property taxes in exchange for a percentage of the savings. Before signing up with one of them, I wanted to understand what they'd actually be doing for that money. So I started reading. The further I got, the clearer one thing became: every California county has a free informal review. You submit comparable sales evidence to your county Assessor's office, a certified appraiser looks at it, and your assessed value either goes down or stays the same — in this review, the Assessor can't raise it. Most homeowners don't know this path exists. The mailers don't mention it.
So I filed on my own home, here in Alameda County, where I live. I used that free informal review — the same process this site walks you through. I pulled comparable sales for homes like mine, put the evidence together, and sent it to the Assessor. They agreed, and brought my assessed value down. It wasn't a rounding error — it was a real cut to my tax bill. A reduction like this is temporary by design: the Assessor revisits the value every year, and as the market recovers the assessment can climb back toward my original Prop 13 value — never above it. So it isn't one-and-done; some years I may have to make the case again. But this year's savings were real, and I'd have left them on the table if I hadn't known to ask. I did the thing myself before I ever asked anyone else to. And once you've seen how it's supposed to work, watching companies charge homeowners — including people who are already stretched and looking for places to save — a quarter of their savings for what is mostly paperwork feels like exactly the kind of friction the system shouldn't have.
What I've done: read the published guidance from the California State Board of Equalization (the state authority that oversees property tax assessment) on Proposition 8 and assessment appeals; mapped the deadlines, forms, fees, and submission paths for the six California counties Overassessed serves today; and won a reduction on my own home through that same informal review. Every county page on this site lists the date its facts were last verified, with a link to the source.
What this site isn't: a promise that your county will say yes. That decision belongs to your county, not to us, and I won't pretend to control it. What I will promise is our fee: buy a Filing Guide, file your appeal with it, and if the county denies you any reduction at all, email us the decision letter and we refund you in full. Any reduction — full or partial — is a win, and it's yours to keep.
If you find an error on any page, email me at stu@overassessed.co. I read every email.
Overassessed is built and operated by Spaghetti Labs, LLC, a small California company. Behind it is a real, named person you can email — not a call center that bought a list with your name on it.
How we make money
Fair question — you should ask it of anyone who wants to get near your money. The companies in those mailers take a cut of your savings, often a quarter, every year you keep the lower assessment. We don't work that way.
The check is free — no credit card, no email, no account. If it turns out you have a case and you want the evidence packaged and ready to file, that's the one time you'd pay: $45, once. Not a percentage of your savings, not a subscription, nothing to remember to cancel. If you don't have a case, we'll tell you, and you owe us nothing. We'd rather charge once and let you keep all of your reduction.
Denied by the county? You get your money back.
Get a reduction or get your $45 back. If you file with a Filing Guide and the county denies you any reduction, email us the decision letter and we refund you in full, within five business days. See the guarantee terms
How we build our county guides
Every fact on a county page — the filing deadlines, the fees, the forms, and who you send them to — comes straight from the source: your county Assessor's office, the county Clerk of the Board, and the California State Board of Equalization, the state authority that oversees assessment. We don't rely on the third-party sites that repackage this information and get it wrong. Where we can, we link you to the official page so you can check it yourself.
County rules change, so we re-check every county's facts on a set schedule — at least four times a year — and every county page shows the date we last verified it against the source. When a county changes a deadline or a fee, we fix it in one place, so the number you read on one page is the same everywhere on the site.
What we do is simple to say: we turn a confusing public process into a guide a homeowner can actually follow. We don't give legal or tax advice, we don't represent homeowners at hearings, and we don't file appeals for you.
Spotted something wrong on a county page?
County websites change. We aim to verify our county facts at least quarterly, but if you see something out of date, send a note to stu@overassessed.co. We'll fix it and credit you on the page.
Want to see if you're overpaying?
Enter your address and we'll compare your assessed value to recent comparable sales. We use it to pull public records — that's all. No account, no sales calls. Free, and about 60 seconds.