California Property Tax Appeal Guide 2026

To assessment appeal your property taxes in California, you file with your county Assessment Appeals Board (Form BOE-305-AH) by the deadline on your assessment notice (shown below). This guide covers how the assessment appeal works, the assessment ratio, what evidence helps, and where to file. General information, not legal advice.

Deadline: July 2 through September 15 (or November 30 / December 1 in counties that don't mail assessment notices to all owners by August 1). Supplemental assessments: 60 days from the supplemental notice.

Missing the deadline permanently waives your assessment appeal for that year. Confirm the exact date on your own assessment notice before acting — it varies by county.

How to assessment appeal your property taxes in California

You file with your county Assessment Appeals Board (Form BOE-305-AH). Start by reviewing your assessment notice, gather evidence that your value is too high (recent comparable sales, an appraisal, or condition issues), and submit by the deadline above. Review the official process and forms here: California official filing information.

What is the California assessment ratio?

100% of base-year value, capped at 2%/year growth under Proposition 13. Because the assessed value is locked to your purchase price and rises slowly, long-tenured owners are usually already well below market — and have little reason to appeal. A Proposition 8 'decline-in-value' reduction is available when current market value drops below your base-year value.

California property tax at a glance

Process	assessment appeal
Deadline	July 2 through September 15 (or November 30 / December 1 in counties that don't mail assessment notices to all owners by August 1). Supplemental assessments: 60 days from the supplemental notice.
You file with	your county Assessment Appeals Board (Form BOE-305-AH)
Median home value	about $789,000
Median effective tax rate	about 0.70%

What makes California different

Under Proposition 13, the longer you've owned, the further your assessed value sits below market — so most California homeowners have no reason to appeal, even with the large absolute bills that high home values produce. Appeals are filed mainly by recent buyers who think their purchase-price reassessment was too high, and by owners seeking a Proposition 8 reduction when the market falls below their base-year value.

Frequently asked questions

When can I appeal my property assessment in California?

The regular filing window is July 2 through September 15, extended to November 30 or December 1 in counties that don't mail notices to all owners by August 1. Supplemental assessments have their own 60-day window from the notice date.

Should I appeal if I've owned my home a long time?

Usually no. Proposition 13 caps your assessed value's growth at 2% per year, so long-tenured owners are typically assessed well below market value already — there is nothing to reduce. Appeals make sense mainly for recent buyers or for a Proposition 8 decline-in-value claim.

What is a Proposition 8 decline-in-value reduction?

If your home's current market value falls below your Proposition 13 base-year value, you can apply for a temporary reduction to that lower value. When the market recovers, the assessed value is restored up to your factored base-year value.