How to appeal property taxes in California
The free review, the formal appeal, every county's deadline, and the evidence that actually wins — in the order you'll need them.
In California you appeal your property taxes by challenging your assessed value, and there are two ways to do it. The first is a free informal review with your county assessor, where you submit comparable sales showing your home was worth less than its assessed value on January 1. The second is a formal appeal to your county's Assessment Appeals Board, filed between July 2 and either September 15 or November 30 depending on the county. You can do both, most homeowners start with the free one, and neither requires a lawyer.
The whole thing turns on one piece of evidence: recent sales of homes like yours. Everything below is about getting that evidence in front of the right office before the right date.
Do I have grounds to appeal?
You do if your home's market value on January 1 was lower than its assessed value. California law requires the assessor to enroll the lower of your Proposition 13 value (purchase price plus up to 2% a year) or the January-1 market value (Revenue & Taxation Code § 51). When the higher number is on your bill, your home is overassessed, and the appeal is how you get the lower one enrolled.
The common triggers: you bought near a market peak; prices in your area softened after you bought; your home has condition or location problems the county's records don't capture; or a previous reduction was reversed as the market recovered. What is not grounds: your taxes feeling high, your neighbor paying less, or a market drop that happened after January 1 — that one counts next year.
The fastest first read: our free check pulls your assessed value and compares it to a market estimate for your home. If there's no gap, there's no appeal, and we'll say so.
Check my property for freeThe two ways to appeal: informal review vs. formal appeal
They run on separate tracks with separate offices and separate deadlines. Filing one doesn't affect the other, which is why the standard advice in most counties is: start informal, and file formal before the deadline if you haven't heard back.
| Informal review (decline-in-value) | Formal appeal (Assessment Appeals Board) | |
|---|---|---|
| Who reviews it | A county appraiser in the Assessor's office | A hearing officer or the Assessment Appeals Board (independent of the Assessor) |
| Cost | Free, everywhere | A per-parcel filing fee set by the county; some charge nothing, some waive it for hardship |
| Hearing | None — a desk review of your evidence | Yes — you present evidence, the assessor presents theirs |
| Can your value go up? | No — down or unchanged | In principle yes; the board finds full market value |
| When | Each county sets its own window; a few accept requests year-round | July 2 to September 15 or November 30, by county |
| Form | County's decline-in-value request (or a letter) | BOE-305-AH Assessment Appeal Application, or the county's version |
| Best for | Almost every homeowner — try this first | A backstop before the deadline, or when the informal review is denied |
The informal review is the procedure the assessor sites call a decline-in-value reassessment — a Proposition 8 reduction. The formal appeal is governed by R&T §§ 1603–1604 and Property Tax Rule 305.
How to appeal, step by step
- 1
Find your assessed value
Take the total assessed value from your property tax bill or your Notice of Assessed Value. That number, not your tax amount, is what you're appealing.
- 2
Estimate your home's market value on January 1
Find three to five sales of similar nearby homes that closed as close to January 1 as possible — and no later than March 31, because an appeals board can't consider sales more than 90 days after the lien date (R&T § 402.5). If they point below your assessed value, you have a case.
- 3
Confirm your county's two deadlines
Every county runs a free informal review with its own window, and a formal appeal window that opens July 2 and closes September 15 in some counties and November 30 in the rest. Look yours up before you do anything else.
- 4
File the free informal review with the county assessor
Submit your opinion of value and your comparable sales on the county's decline-in-value form (or a short letter). A county appraiser reviews it; your value goes down or stays the same and cannot go up.
- 5
File the formal appeal as a backstop if the deadline is near
If your informal review hasn't been decided as the formal deadline approaches, file the Assessment Appeal Application (BOE-305-AH, or your county's version) with the Clerk of the Board. It preserves your rights and can be withdrawn if the assessor lowers your value first.
- 6
Present your evidence at the hearing, if it gets that far
Most residential cases resolve informally or through a settlement before the hearing. If yours doesn't, you present your comparable sales to a hearing officer or the Assessment Appeals Board; the assessor presents theirs; the board decides.
- 7
Collect the reduction
A reduction lowers this year's bill (or triggers a refund with interest if you've already paid). Decline-in-value reductions are re-reviewed by the assessor every January 1 automatically — you don't refile unless the value climbs above market again.
Steps 3 through 5 are where counties differ — the form names, the portals, the mailing addresses, the fee. The county guides below carry those specifics; this page stays at the level that's true everywhere.
When is the deadline to appeal property taxes in California?
The formal appeal window opens July 2 in every county and closes on one of two dates, fixed per county under Property Tax Rule 305: September 15 in counties that mail a Notice of Assessed Value to every property owner, and November 30 everywhere else. For 2026, 11 counties close September 15 and 47 close November 30, per the State Board of Equalization's annual filing-period letter.
The September 15 counties: Alameda, Alpine, Inyo, Kings, Mono, Placer, San Francisco, San Luis Obispo, Santa Clara, Sierra, Ventura. If your county isn't in that list, your formal deadline is November 30. When the date falls on a weekend or holiday, it moves to the next business day.
Informal review windows are separate and set by each county assessor. Some run January through spring, some run July into the fall, and a few accept requests year-round — which means the free option can close months before the formal deadline. The county table below shows both dates side by side for the counties we cover in depth; the statewide deadline page lists the formal deadline for all 58 counties. Deadlines change with the state's annual notice; ours were last verified 2026-09-13.
County-by-county: windows, fees, and the detailed guide
Each guide walks through that county's actual forms, portals, and mailing addresses. Every date and fee here renders from the same verified county record the guide uses, so they can't disagree.
| County | Free informal review | Formal appeal window | Formal fee |
|---|---|---|---|
| Alameda County | Accepted year-round | July 2 – September 15 | $50 |
| Contra Costa County | By November 30 | July 2 – November 30 | $40 |
| Los Angeles County | July 2 – November 30 | July 2 – November 30 | $46 |
| Orange County | January 1 – April 30 | July 2 – November 30 | No fee |
| Sacramento County | July 1 – December 31 | July 2 – November 30 | $30 |
| San Diego County | December 1 – April 30 | July 2 – November 30 | No fee |
| San Francisco County | January 2 – March 31 | July 2 – September 15 | $120 |
| San Mateo County | By October 31 | July 2 – November 30 | $30 |
| Santa Clara County | By August 8 | July 2 – September 15 | $290 |
Not in one of these counties? The process above still applies. Find your county's Clerk of the Board through the State Board of Equalization's assessment appeals page, confirm the two dates, and use the statewide BOE-305-AH form.
How much does it cost to appeal?
The informal review is free in every county. The formal appeal carries a per-parcel filing fee set by each county — among the counties in the table above it runs from no fee to $290, and several counties waive it for financial hardship. That is the entire cost the government charges.
The other cost is the evidence. You have three ways to get it: assemble the comparable sales and adjustments yourself (free, budget five to ten hours to do it credibly), pay a flat fee for a prepared evidence packet you file yourself (our Filing Guide is $45, once), or hire a contingency company that files for you and keeps a percentage of your savings — about 35% in California for the two biggest firms, every year they win. Every California option compared lays out when each one makes sense.
What evidence wins a California property tax appeal?
The assessor and the appeals board both weigh the same thing: comparable sales near the lien date, with the differences from your home accounted for.
Counts
- ✓Three to five closed sales of similar homes nearby, as close to January 1 as possible and no later than March 31
- ✓Adjustments that explain each difference — size, bedrooms and baths, lot, condition, view, street — in dollars
- ✓Photos, inspection reports, or contractor estimates for condition problems the county can't see from records
- ✓An income analysis instead of sales, if the property is a rental
Doesn't count
- ✕Zillow, Redfin, or any automated estimate — not tied to the lien date, methodology can't be examined
- ✕Active listings and pending sales — asking prices aren't values
- ✕Your neighbor's tax bill — their Prop 13 base is theirs, not evidence of your market value
- ✕Sales after March 31, or a market drop that happened after January 1
The rules behind that list — the 90-day rule, Property Tax Rule 4 adjustments, what a hearing officer expects to see — are on the evidence page.
Mistakes that lose appeals
Waiting on the informal review past the formal deadline
The informal review doesn't pause the formal clock. If the deadline is close and you haven't heard back, file the formal application too — you can withdraw it later.
Appealing the tax bill instead of the assessed value
The appeals board can't change your tax rate or the bonds on your parcel. The only thing on the table is the assessed value; that's what your evidence has to address.
Arguing from today's market
Only January 1 matters. A drop in June helps you next year, not this one — and comparable sales that closed after March 31 can't be used.
Expecting the reduction to be permanent
A decline-in-value reduction is re-checked every January 1 and rises with the market, capped at your Prop 13 value. It never lowers the Prop 13 base itself.
Paying a percentage for work that takes fifteen minutes
Full-service companies are legitimate, but in California's informal process the filing itself is short once the evidence exists. Get the evidence, file it yourself, and keep the savings.
Common questions
Two ways, and you can use both. First, ask your county assessor for a free informal decline-in-value review: submit comparable sales showing your home was worth less than its assessed value on January 1, and a county appraiser lowers your value or leaves it alone. Second, file a formal Assessment Appeal Application (BOE-305-AH) with your county's Clerk of the Board between July 2 and your county's deadline — September 15 or November 30 — for a hearing before the Assessment Appeals Board. Most homeowners start with the informal review and file the formal appeal only as a backstop before the deadline.
The formal appeal window opens July 2 every year and closes on September 15 in counties that mail assessment notices to every property owner, and on November 30 everywhere else (Property Tax Rule 305). Which date applies is fixed per county — the State Board of Equalization publishes the list each summer. Informal review windows are set by each county assessor separately and can close months earlier, so check both dates for your county.
The informal review with the assessor is free in every county. The formal appeal has a per-parcel filing fee set by each county — from nothing in some counties to a few hundred dollars in others — and several counties waive it for hardship. Beyond the fee, the only cost is assembling the comparable-sales evidence yourself, paying a flat fee for it, or paying a contingency company a percentage of your savings every year.
Not through the informal review — the assessor can only lower your value or confirm it. In a formal appeal the Assessment Appeals Board determines full market value and can, in principle, raise it if the evidence shows the property was under-assessed. That's rare for a home whose owner has comparable sales in hand, but it is why the informal review comes first.
Closed sales of comparable homes near the January 1 lien date, with adjustments for the differences between them and your home — size, condition, lot, location. Sales that closed more than 90 days after January 1 can't be considered by an appeals board (R&T § 402.5). Automated estimates, listing prices, a neighbor's tax bill, and what you paid years ago don't count as evidence of value.
No. California's informal review is designed for homeowners, and the formal appeal hearing is an informal administrative proceeding where homeowners routinely represent themselves. You can authorize an agent if you want one, but the evidence a professional submits — comparable sales with documented adjustments — is the same evidence you can submit.
Informal reviews typically resolve within weeks to a few months, depending on the county and when you file. Formal appeals take longer — the board has up to two years from filing to hold your hearing, though most residential cases are decided well before that. Either way, keep paying your tax bill on time; a win is refunded with interest.
The regular deadline has no extension, but the next informal window and the next formal window open again the following year, and the January 1 lien date resets what you're arguing about. Some counties accept informal requests year-round. A supplemental or escape assessment carries its own 60-day appeal clock from the notice date, separate from the regular window.
Start with step one: are you overassessed?
Enter your address and we'll compare your assessed value to a market estimate for your home — free, about 60 seconds, no account.
If you qualify and want the evidence prepared, the Filing Guide is $45 once — never a percentage of your savings.
This is general information about California's assessment appeal process, not legal or tax advice. County deadlines, fees, and forms are verified against county and State Board of Equalization sources as of 2026-09-13 and can change; confirm with your county's Clerk of the Board before relying on a date. Appeal outcomes depend on the county's review of your evidence.