Supplemental Property Tax Bills in LA County, Explained
Figures and rules in this post are as of November 6, 2026, from the sources linked below. Check the source for any later update.
In California, a change of ownership or completed new construction triggers a reassessment. In Los Angeles County, the Assessor sets the new value and the Treasurer and Tax Collector bills the difference between the old and new assessed values for the rest of the fiscal year. That is the supplemental tax bill.
Key points
- It is a separate bill from the annual secured tax bill.
- It can arrive months after closing.
- It is often sent to the owner, not the lender. Impound accounts don’t always cover it, so ask your lender.
- If the new value is lower than the old one, the result can be a refund instead of a bill.
Why it matters for buyers
The seller’s current tax bill may be based on an older, lower assessed value. A buyer’s ongoing taxes are based on the new assessed value, generally the purchase price, plus any voter-approved assessments and direct charges. Estimate taxes from the purchase price, not the seller’s bill.
You can look up a property’s assessment on the LA County Assessor’s property portal.
Sources
- LA County Office of the Assessor
- LA County Assessor property portal
- LA County Treasurer and Tax Collector
Questions about a home in Los Angeles or the Valley?
Lianna Danielyan, REALTOR® · Equity Union · CA DRE #02142653 · 13400 Ventura Blvd, Sherman Oaks, CA 91423 · (818) 669-6245
Listing information is provided through Equity Union’s IDX/BoldTrail service, is deemed reliable but not guaranteed, and should be independently verified. Information on this page is general and is not legal, tax or financial advice. Equal Housing Opportunity.