Home › Guides
RP-87 vs AAB-100: which LA County form should you file?
Updated November 4, 2026 · For Los Angeles County homeowners
LA County homeowners who think their 2026 assessed value is too high have two forms to choose from. Short answer: if your evidence is solid and the deadline is close, file both.
| RP-87: Decline-in-Value Review | AAB-100: Assessment Appeal | |
|---|---|---|
| Filed with | LA County Assessor | Assessment Appeals Board |
| Cost | Free | Filing fee (non-refundable) |
| 2026 filing window | July 2 – November 30, 2026 | July 2 – November 30, 2026, until midnight Pacific |
| How to file | Online on the Assessor's Decline-in-Value page, or by mail | Online at lacaab.lacounty.gov, or by mail |
| Who decides | An Assessor's appraiser reviews it | An independent hearing officer or appeals board |
| Hearing | No | Yes, if you don't settle first |
| Best for | Clear cases with good comparable sales | Keeping your rights if the review doesn't lower your value |
Why many people file both
The Assessor's review may not be finished by November 30. If you only file the RP-87 and it comes back with no change after the deadline, it's too late to file a formal appeal for 2026. Filing the AAB-100 too protects your right to a hearing. If the Assessor lowers your value first, you can usually withdraw the appeal.
What you need for either form
- Your Assessor's ID Number (AIN), printed on your tax bill
- Your 2026 assessed (roll) value
- Your opinion of value as of January 1, 2026, ideally the median of adjusted comparable sales
- 3–5 comparable sales from before about April 1, 2026, which California's 90-day rule requires (Revenue and Taxation Code §402.5)
Not sure what value to write? Our step-by-step guide explains how to pick comparable sales and work out the number. Or let us check your home for free.
Check my home for freeThis guide is general information, not legal or tax advice. Property Tax Appeal Now is independent and not affiliated with Los Angeles County.