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Not a government agency. You can request a free review from the Assessor or appeal on your own. Read the California disclosure

THIS ASSESSMENT REDUCTION FILING SERVICE IS NOT ASSOCIATED WITH ANY GOVERNMENT AGENCY. IF YOU DISAGREE WITH THE ASSESSED VALUE OF YOUR PROPERTY, YOU HAVE THE RIGHT TO AN INFORMAL ASSESSMENT REVIEW, AT NO COST, BY CONTACTING THE ASSESSOR’S OFFICE DIRECTLY. IF YOU AND THE ASSESSOR CANNOT AGREE TO THE VALUE OF THE PROPERTY OR IF YOU DO NOT WISH TO CONTACT THE ASSESSOR YOU CAN OBTAIN AND FILE AN APPLICATION FOR CHANGED ASSESSMENT WITH THE COUNTY BOARD OF EQUALIZATION OR ASSESSMENT APPEALS BOARD ON YOUR OWN BEHALF. AN APPEALS BOARD HAS THE AUTHORITY TO RAISE PROPERTY VALUES (BUT IN NO CASE HIGHER THAN THE PROPOSITION 13 PROTECTED VALUE) AS WELL AS TO LOWER PROPERTY VALUES.

California condo owners: lower your property tax.

We review your assessment and handle your appeal. You pay only if we win.

Sign up your unit →

$0 upfront. Our fee is 35% of your first-year savings, only if we win. If your properties with Castellan are assessed at more than $5 million combined, your rate is 30% on everything.

Your assessment should reflect the market.

A building's market can change while individual assessments stay high. We check your unit's assessment and tell you whether there is a case for a reduction.

Most successful appeals cut assessed value 15–40%.

Appeal deadlines

Most California counties close November 30. See your deadline

County2026 deadlineStatus
Los Angeles CountyNovember 30, 2026Open
Orange CountyNovember 30, 2026Open
San Diego CountyNovember 30, 2026Open
Riverside CountyNovember 30, 2026Open
San Bernardino CountyNovember 30, 2026Open
Ventura CountySeptember 15, 2026Closed for 2026
Sacramento CountyNovember 30, 2026Open
Placer CountySeptember 15, 2026Closed for 2026
El Dorado CountyNovember 30, 2026Open
Yolo CountyNovember 30, 2026Open

Los Angeles County building directory

What happens after you sign.

01

Analyze your building and comps.

We comb hundreds of comps across public records and paid private market data, check them against the county's file and your own documents, and build the narrative and evidence packet your county's rules require.

02

File when there's a case.

If your value is already in line, we tell you and nothing gets filed. If it isn't, we prepare the appeal and file it inside your county's window.

03

Negotiate with the county.

Most reductions are negotiated with the assessor's office after the filing, and we handle that exchange.

04

Appear at the hearing.

When a hearing is needed, we prepare the evidence and appear in front of the board for you. We tell you when there is a result.

Your part is signing the forms and sending documents when we ask.

What you pay, and when

  1. Nothing now, and nothing if we don't win.
  2. When you sign up, save a card or US bank account. Autopay earns a credit of 2% of our fee — for every $100 we charge, you pay $98.
  3. If we win a lower assessed value, your property tax falls with it.
  4. Then we charge 35% of the tax savings for the year, plus county fees we advanced at cost. Our rate falls to 30% when your combined assessed value exceeds $5,000,000. Nothing on file? We email the bill, due in 30 days.
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Own more than one unit?

Add your units to the same signup, including homes in other buildings. Each property keeps its own assessment and appeal.

Talk to us

Questions

How do you know my property is over-assessed?
We compare the county's assessed value against its own records for genuinely comparable properties, plus public sale records. If your value is already in line, we'll tell you, and there's nothing to file.
Will every unit get a reduction?
No. Each unit has its own assessment and evidence. A low existing assessment or resale restrictions can change whether an appeal is worthwhile. We review the unit before filing.
Does a reduction last forever?
A California decline-in-value reduction is reviewed annually. Future assessed values can rise again, up to the Proposition 13 protected value. The agreement explains how future-year reviews and fees work.
Can my appeal make my assessment go up?
In some states a review board can raise a value as well as lower it. That is why we check for that exposure before we file: we do not file when we see it, and if it appears after filing we withdraw.
What do I need to sign up?
Your unit number, your contact information, and the authority to sign for the owner. We look up the property record. If we need documents for the case, we will ask for them.
My unit is in an LLC or trust
Sign as the person authorized to act for that owner and enter the ownership details in the signup form.
Does this change HOA dues?
No. This service concerns property tax assessments, not HOA dues or fixed charges on your tax bill.
What happens after this year's appeal?
Free assessment monitoring continues every year until you cancel; you don't need to sign up again. We pursue another appeal when we determine there's a case worth filing. We notify you first and arrange any new owner authorization or signature your county requires before filing.

Keep paying your property tax bills while the appeal is pending. Filing an appeal does not suspend payment deadlines.

Sign up your unit.

Sign up your unit → Book a 15-minute call
Emailinfo@castellan.so

Questions? Email us or book a call.

Castellan is a private company, not a government agency. Potential savings are estimates, not a promise.