Overassessed in a county we haven't fully mapped yet? You can still appeal.
The hard part of a property tax appeal is the evidence, and evidence works the same in all 58 California counties. We build yours; you file it with our statewide roadmap.
Overassessed offers full step-by-step filing support in Alameda County, Los Angeles County, San Diego County, Santa Clara County, Orange County, San Mateo County — counties where we've personally verified every portal, form, fee, and deadline. Everywhere else in California, we offer the Appeal Evidence Kit: the same analysis engine behind our Filing Guide, paired with honest statewide filing guidance instead of county-specific walkthroughs we haven't researched yet.
That trade works because California standardizes what matters. Proposition 8 (Revenue & Taxation Code §51) requires every county assessor to tax you on the lower of your Prop 13 value or the January 1 market value. The formal appeal runs on a statewide application, filed with your county's Clerk of the Board, in a window that opens July 2 everywhere. What actually varies by county — the local portals and paperwork — is the part a homeowner can handle in an afternoon with good directions. The part you can't do in an afternoon is the evidence. That's what you're buying.
What you get — and what you don't
In the kit
- • Comparable sales selected and adjusted for your property, with the reasoning shown
- • A defensible opinion of value and requesting value
- • A professional evidence PDF: comparison grid, written value argument, neighborhood map
- • A ready-to-sign informal review request letter, plus a submission packet built to mail or email as-is
- • Your county's verified appeal deadline, assessor phone and website (from official state sources)
- • The California filing roadmap: form values for the statewide BOE-305-AH application, what to expect, and rebuttal and negotiation prep for your eyes only
Not in the kit (we'll say it before you pay, too)
- • Click-by-click walkthroughs of your county's portals — we haven't verified them yet
- • Pre-filled county form PDFs (a fully-supported-county feature)
- • Your county's exact filing fee — many counties charge nothing; some charge a processing fee. Confirming it takes a minute when you get the form
When your county gets full support, you'll be first to know — kit buyers are how we pick what to build next.
How filing works, anywhere in California
- 1
We build your evidence
Recent comparable sales near your property, adjusted dollar-for-dollar for size, age, lot, and timing against the January 1 lien date — the standard county appraisers actually apply.
- 2
You send the free informal request
Your kit includes a signed-ready request letter and a submission packet. Mail or email it to your county Assessor's office — the Assessor can only lower your value or leave it alone.
- 3
You protect the deadline
If the formal appeal deadline approaches — September 15 or November 30, depending on your county — file the statewide application with your Clerk of the Board using the values in your kit. You can withdraw it later if the informal review succeeds.
- 4
The county responds
Many cases settle when an appraiser reviews credible comparable sales evidence. If yours goes to a hearing, your evidence packet and meeting prep are built for exactly that.
Deadlines vary by county — see the 2026 deadline for all 58 counties.
Questions homeowners ask
They share the same analysis engine: comparable sales selected and adjusted for your property, a defensible opinion of value, a professional evidence PDF, rebuttal preparation, and negotiation guidance. The Filing Guide adds county-researched, click-by-click filing instructions — we've verified the portals, forms, fees, and windows for those counties. The kit replaces that piece with a statewide California roadmap plus a ready-to-send request letter, because we haven't researched your county's local process yet. We say that plainly before you buy.
Here's the honest version: California law (Revenue & Taxation Code §51(a)(2)) requires every county assessor to enroll the lower of your Prop 13 value or the January 1 market value — but the law doesn't require counties to run a formal 'informal review program.' Most do anyway, because fixing values informally is cheaper than defending appeals. Either way, you can always submit evidence and ask. That's why the kit includes a ready-to-sign request letter that works in every county, program or no program.
Every California county's formal appeal window opens July 2 and closes either September 15 or November 30, depending on whether your assessor mails value notices to everyone by August 1. We track the official State Board of Equalization list for all 58 counties — your kit shows your county's exact date, and our deadlines page lists every county's.
No. In an informal review the Assessor can only lower your assessed value or leave it unchanged — it cannot go up. The one thing to know: an informal request does not pause the formal appeal deadline. Your kit keeps that date in front of you and includes everything you'd need to file the formal appeal as a backstop.
The Appeal Evidence Kit is $35, one time. The same guarantee as our Filing Guide applies: if the county denies the appeal you file with our kit, email us the decision letter and we refund you in full.
Start with the free check
Enter your address and we'll compare your assessed value to the market — free, in any California county. Not everyone qualifies. Let's find out.