The Market Moved.
Your Assessment Didn't.
Prop 13 caps how fast your taxes climb — it doesn't guarantee your assessed value is right. Supplemental assessments, stale decline-in-value reviews, and disaster-damaged property are over-taxed across California every year. If your home is worth less than its taxable value on January 1, the law says you're owed a reduction.
Two Deadlines. One Applies to You.
Unlike most states, California's appeal window closes on different dates depending on your county. Eleven counties cut you off September 15. The other forty-seven give you until November 30. Pick your county to see your window.
County deadlines are certified annually under Rev. & Tax. Code §1603 and can change year to year. September 15 counties shown per the BOE's most recent published filing-period list — always confirm with your county clerk of the board before relying on a date. Deadlines falling on a weekend or holiday roll to the next business day.
Prop 13 Protects the Cap. Not the Number.
Your taxable value only has to be right on one day — January 1. Here's where California assessments go wrong, and where the law is on your side.
The market fell. Your roll value didn't follow.
When your home's market value on January 1 drops below its Prop 13 factored base year value, the assessor is required to enroll the lower number. Assessors don't always catch it — especially in soft or correcting markets. You have to ask, and you have to prove it with comparable sales.
You bought or built — and got reassessed high.
A change in ownership or new construction triggers a supplemental assessment at "current market value." If the assessor's number is above what you actually paid — or above what the market supports — you can appeal the new base year value and lock in a lower ceiling for every year after.
A wrong base year compounds forever.
Your base year value is the ceiling that grows up to 2% per year for as long as you own the property. If it was set too high at purchase or after construction, you overpay every single year. Base year appeals can generally be filed in the year the value is set or the three following years.
Fire, flood, or quake damaged your property.
California law provides for reassessment of property damaged or destroyed by misfortune or calamity — wildfire included. Most counties require a claim within 12 months of the damage. If your property was hit and your assessment wasn't reduced, you're being taxed on value that burned.
Once you file a timely appeal, the Assessment Appeals Board generally must hear and decide your case within two years — or your opinion of value goes on the roll by default (with limited exceptions, and unless you agree to an extension). Filing on time is everything. Missing the window means waiting a full year for another shot.
Two Paths to a Lower Assessment.
California gives you an informal route and a formal one. Smart filers often take both — request the free review, and file the formal appeal before the deadline as insurance.
Informal Review
Free- Request a Prop 8 decline-in-value review directly from your county assessor — most counties have a simple online or one-page form
- No hearing, no board, no filing fee
- Strongest when backed by comparable sales near the January 1 lien date — exactly what our comp engine produces
- Assessor can reduce your value without you ever appearing anywhere
Formal Appeal
BOE-305-AH- File the Assessment Appeal Application with your county's Clerk of the Board during the filing window
- Heard by the Assessment Appeals Board — an independent, quasi-judicial panel, not the assessor
- Preserves your rights: an informal review that stalls past the deadline leaves you with nothing unless you also filed
- Some counties charge a small processing fee; most residential filers represent themselves
Our packet covers both. The same evidence file — comps, condition report, valuation narrative — works as your informal review submission and as your hearing exhibit if you go formal. File once, argue everywhere.
Four Steps to a Winning Appeal.
Enter Your Property
Look up your parcel by address or APN. Your assessed value, factored base year value, and property details load from county roll data.
Load Comparables
Pull comparable sales bracketing the January 1 lien date — the sales that matter under Rule 324. Distressed and below-roll comps sorted first.
Upload Photos
Our AI analyzes your photos — deferred maintenance, fire or water damage, dated systems — and produces a formal condition report you can cite.
Get Your Packet
Download everything: auto-filled BOE-305-AH, informal review letter, comp table, condition report, valuation model, and a ready-to-read hearing statement.
Built on Real California Data.
Statewide Parcel Coverage
Roll values, factored base year values, and assessment history for parcels across all 58 counties, from county assessor and public record data.
All TiersAI Photo Condition Assessment
Upload photos of damage, dated kitchens, worn systems, or deferred maintenance. AI returns a condition rating, percentage adjustment, and specific findings for your hearing.
Free: 5 · Entry: 25 · Top: 100 · Multi: 100/propertyLien-Date Valuation Model
Sales-comparison valuation anchored to your January 1 lien date, weighted toward the comps an Appeals Board actually credits, with a defensible opinion of value and formal narrative.
Top & MultiBOE-305-AH Auto-Fill
California's Assessment Appeal Application, auto-filled with your parcel data, appeal type (decline in value, supplemental, base year, calamity), and opinion of value. Download, sign, file with your Clerk of the Board.
Top & MultiInformal Review Letter
A ready-to-send Prop 8 decline-in-value request addressed to your county assessor, with your comp table attached — the free path, done properly.
Entry · Top · MultiComplete Hearing Packet PDF
Cover letter, property summary, comp table with $/sf, condition report with photo findings, valuation narrative, and a formatted verbal statement for your Appeals Board hearing. Print it. Bring it. Win.
Top & MultiFire-Damaged Property Deserves a Reset.
California's recent wildfire seasons destroyed or damaged tens of thousands of structures — and left many more properties with smoke, ash, and market stigma that the assessment roll never caught up with. State law provides real relief, but almost none of it is automatic. You have to claim it, on time, with evidence.
- Section 170 calamity reassessment — property damaged or destroyed by misfortune or calamity can be reassessed downward for the period of damage. Most counties require a claim within 12 months.
- Restored value, not re-based — rebuild comparably and your Prop 13 factored base year value comes back; you shouldn't be re-assessed at new-construction market value for a like-for-like rebuild.
- Prop 19 disaster transfers — owners whose primary residence was substantially damaged in a governor-declared disaster may transfer their base year value to a replacement home anywhere in the state.
- Smoke, stigma & proximity — even undamaged homes near burn scars can qualify for Prop 8 decline-in-value relief when January 1 market value falls. Our comp engine surfaces the post-fire sales that prove it.
If your parcel sits in or near a declared disaster area, your packet flags the calamity and disaster-relief programs you may qualify for — alongside your standard appeal evidence.
Simple, One-Time Flat Fees.
No subscriptions. No contingency cuts — appeal firms in California routinely take 25–50% of your first-year savings. Pay once per appeal, keep every dollar you save.
Free
Find out if you have a case
- County deadline & appeal-type checker
- Up to 5 property photos analyzed
- Basic AI condition rating
- Lien-date comp table (current year)
- Over-assessment estimate
- Printable appeal summary
Entry
The free informal path — done properly
- Everything in Free
- Up to 25 photos analyzed
- Informal Prop 8 decline-in-value review letter, addressed to your county assessor
- Formatted comp table exhibit attached
- Filing instructions for your county's review process
Top
The complete formal appeal — informal letter included
- Everything in Entry
- Up to 100 photos per property, detailed AI condition report
- Comp data across 3 assessment years
- Lien-date valuation model & narrative
- BOE-305-AH auto-filled PDF — ready to sign
- Complete hearing packet PDF
- AI hearing statement tailored to your property
- Calamity / disaster relief flags where applicable
Multi
Everything in Top, for every parcel you own — priced per property with volume breaks, starting at 4 properties. One order, one filing season, the whole portfolio.
- 100 photos per property with full AI condition report
- CSV / bulk parcel import by APN
- Batch BOE-305-AH — one signed-and-ready form per parcel
- Batch hearing packets — one PDF per property
- Income approach valuation for rental property
- 5 years of comparable sales history
- Appeal candidates report across your zip codes
- First-year Prop 8 January re-check included on every parcel — renews at $12/property/yr
- Priority analysis & direct support line
County filing fees are separate: some California counties charge their own per-application processing fee (typically $30–46) collected by the Clerk of the Board — those are paid by you at filing, not included here. You sign and file your own applications; we generate the documents.
Why flat fees? Traditional California appeal firms work on contingency — commonly 25–35% of your first-year savings, per property, sometimes recurring. On a typical successful appeal that's a $250–350+ cut of money the law already says is yours. Every tier here is a one-time flat fee: you keep the reduction, this year and every year after.
Built for California. Around California Law.
Evidence the board credits
Appeals Boards weigh comparable sales close to the January 1 lien date above everything else. Our comp engine is built around that rule — not generic "Zestimate" logic.
The right appeal type, every time
Decline in value, supplemental, base year, calamity — checking the wrong box on BOE-305-AH can sink a valid appeal. We pick the right type from your facts and fill it accordingly.
No contingency cut
Traditional California appeal firms charge a percentage of your savings, year after year in some cases. A flat one-time fee keeps the reduction where it belongs — with you.
Common Questions.
What is form BOE-305-AH and do I need it?
When is the filing deadline?
What's the difference between an informal review and a formal appeal?
What is a Prop 8 decline-in-value reduction?
Do I need a lawyer or appraiser?
What happens after I file?
Does filing an appeal delay my tax bill?
My property was damaged in a wildfire. What relief exists?
How does the AI condition assessment work?
Is this legal advice?
Don't Let Your County's Deadline Pass You By.
Appeal your assessment in any of California's 58 counties. Start your free appeal now — no credit card required. Takes less than 15 minutes.