If you bought a home in Contra Costa County this year and live in it, file for the homeowners' exemption. It takes $7,000 off your assessed value, and the deadline for the full amount is February 15. It is a small savings every year, but it is easy to miss because the form arrives in the mail months after closing.
Here is who qualifies, the deadlines, and what else new owners should watch for on their first tax bills.
What is the homeowners' exemption worth?
The California State Board of Equalization describes it as a $7,000 reduction in the taxable value of a qualifying owner-occupied home. The Contra Costa County Assessor says it reduces the annual property tax bill by at least $70 each year.
Who qualifies?
The home must be the owner's principal place of residence as of 12:01 a.m. on January 1. The claimant must be an owner, co-owner or a purchaser named in a contract of sale, and only one exemption is allowed per dwelling unit. A rental or second home does not qualify.
What are the deadlines?
According to the county's claim form:
- By 5 p.m. on February 15: the full exemption is available.
- February 16 through December 10: 80 percent of the exemption is available.
- After a supplemental assessment: file within 30 days of the Notice of Supplemental Assessment.
The BOE describes it as a one-time filing with the county assessor. Once granted, it stays in place until you are no longer eligible, and it is your responsibility to tell the assessor if that happens, such as when you move out and rent the home.
How do you file?
The Contra Costa County Assessor mails an application within several months of a purchase and asks owners to return it as soon as possible. The state form is BOE-266, Claim for Homeowners' Property Tax Exemption. If you closed this year and have not seen it, contact the assessor rather than waiting.
What else should new owners watch for?
A purchase also triggers a supplemental tax bill for the difference between the old and new assessed values. The county notes that supplemental bills go to the owner even if you have an impound account, so do not assume your lender will pay it. I explained how that bill works in the property tax bill nobody warns you about.
If you are planning a remodel, see also whether a remodel reassesses your property taxes.
Frequently asked questions about the homeowners' exemption
How much is the homeowners' exemption in California?
It reduces the assessed value of a qualifying owner-occupied home by $7,000. The Contra Costa County Assessor says that saves at least $70 a year on the tax bill.
What is the deadline to file for the homeowners' exemption?
February 15 for the full exemption. A claim filed from February 16 through December 10 receives 80 percent of the exemption.
Do I have to file every year?
No. The BOE describes it as a one-time filing. It stays in place until you are no longer eligible, and you must notify the assessor if that happens.
Which form do I use?
Form BOE-266, Claim for Homeowners' Property Tax Exemption. The Contra Costa County Assessor mails it to new owners within several months of the purchase.
Can I claim the exemption on a rental or second home?
No. The home must be your principal place of residence as of January 1.
The Bottom Line on the Homeowners' Exemption
If you bought and moved into a Contra Costa home in 2026, look for the assessor's form and return it by February 15. While you are at it, watch for the supplemental tax bill, which comes to you even if you have an impound account.
Just bought, or thinking about it?
If you have a question about a tax bill or a form from the assessor after closing, send it to me and I will help you figure out who to call.
Find out what your home is worth
Or call or text 925-250-9611.
Sources
California State Board of Equalization, Homeowners Exemption, for the amount, eligibility, the February 15 deadline, the one-time filing and form BOE-266. Contra Costa County, New Property Owners, for the savings, the mailed application and supplemental bills. Contra Costa County, Claim for Homeowners Property Tax Exemption, for the filing deadlines and who may claim (all checked September 2026).
Jaz Chand, Broker Associate | Homes With Accent
The Jaz Team at Merrill Signature Properties | DRE #01751823
Phone/Text: 925-250-9611 | Jaz@HomesWithAccent.com
General information only, not tax advice. Confirm deadlines and eligibility with the Contra Costa County Assessor.