The tax bill that catches new Brentwood owners is the one that never arrives. Contra Costa County mails the annual Secured bill once a year, by November 1. If you close after that mailing, no bill comes to you, and the county is explicit that not receiving one does not relieve you of paying on time or excuse late penalties.
Then, weeks or months later, a second bill shows up that you were never told about. Here is how the whole thing actually works, and what to do in the first thirty days after you close.
The annual bill, and the two dates that matter
Contra Costa mails the annual Secured property tax bill once a year, by November 1. It is paid in two installments.
First installment: due November 1, delinquent after December 10. It covers July 1 through December 31.
Second installment: due February 1, delinquent after April 10. It covers January 1 through June 30.
Note that the county's tax year starts in July, not January. That mismatch is behind a lot of confusion about which period a payment covers and who owes what at closing.
If your lender pays taxes through an impound account, you may receive an information copy only. Read it anyway. An impound account is only as accurate as the figure the servicer estimated, and that estimate is often built before the county reassesses your purchase.
The supplemental bill, which is the real surprise
When a property changes ownership, the county reassesses it. The difference between the old assessed value and the new one, for the remainder of the tax year, comes to you as a supplemental tax bill. New construction and substantial additions trigger the same thing.
Three things about it catch people.
It is separate from the annual bill. It arrives on its own schedule, sometimes months after closing.
There can be more than one. The county says a change of ownership may generate one or more supplemental bills, depending on when in the tax year it happened.
Your impound account probably does not cover it. Lender impounds are generally set up for the annual bill. A supplemental bill is frequently the owner's to pay directly, and finding that out late is how a manageable amount becomes a delinquent one.
Contra Costa publishes a Supplemental Estimator that lets you work out the likely amount before it arrives. Use it during escrow rather than after. If you are buying in Brentwood, run it as soon as you are in contract and set the money aside. This single step prevents the most common tax surprise I see.
Reading the bill line by line
A Contra Costa bill is not one number. It has parts, and in Brentwood the parts matter more than in most cities.
The ad valorem portion. This is the percentage-of-value piece, the part most people mean when they say property tax.
Voter-approved debt. Bonds that fund schools and other facilities, levied as an additional rate.
Special assessments and direct charges. Fixed-dollar line items. Lighting and landscaping districts, flood control, and other local charges appear here.
Mello-Roos, if the property is in a district. Brentwood has four Community Facilities Districts, and a special tax appears as its own line. It has a maximum and an end date that the annual bill does not show you. Our guide to finding out what a Brentwood address actually owes covers how to get those numbers.
Two Brentwood homes at the same price can carry meaningfully different bills because of the bottom half of that list. Comparing list prices without comparing bills is comparing the wrong thing.
What to do in your first thirty days as an owner
Look up your parcel. Find your Assessor's Parcel Number and look the account up on the county site. Do not wait for paper.
Confirm whether a bill has already been issued for the current year and whether it was paid at closing. Escrow often handles the current installment, and often does not handle the next one.
Run the Supplemental Estimator and set that amount aside.
Ask your servicer, in writing, what the impound covers. Specifically: does it include the supplemental bill, and has the impound been recalculated on your purchase price rather than the prior owner's assessment.
Diarize December 10 and April 10. Not November 1 and February 1. The delinquency dates are the ones with penalties attached.
If you're buying or selling in Brentwood
If you're buying: run the county's Supplemental Estimator while you are in escrow and set that money aside, because your impound account probably does not cover it. Look your parcel up by APN rather than waiting for paper, especially in your first year. Diarize December 10 and April 10, not November 1 and February 1, because the delinquency dates are the ones carrying penalties.
If you're selling: do not let a buyer estimate their taxes from your bill. If you have owned a long time your assessed value is likely well below market and their picture will look nothing like yours. Have the current bill and the special assessment lines ready so the question gets answered once, accurately, rather than becoming a negotiating point late in escrow.
Frequently asked questions about Brentwood property taxes
When are Contra Costa property taxes due?
The annual Secured bill is mailed once a year by November 1 and paid in two installments. The first is due November 1 and delinquent after December 10. The second is due February 1 and delinquent after April 10.
What happens if I never receive a property tax bill?
You still owe the tax on time. Contra Costa County states that failure to receive a bill neither relieves you of responsibility to pay on time nor excuses late-payment penalties. Look your account up by parcel number rather than waiting for mail, especially in your first year of ownership.
What is a supplemental tax bill?
When a property changes ownership or new construction is completed, the county reassesses it, and the difference for the remainder of the tax year is billed separately as a supplemental tax bill. It is in addition to the annual bill, and a change of ownership can generate more than one.
Does my mortgage impound account pay the supplemental bill?
Often not. Impound accounts are generally set up for the annual bill. Ask your servicer in writing whether the supplemental is included, and set the money aside if it is not.
Why do two Brentwood homes at the same price have different tax bills?
Because the bill is more than the percentage-of-value portion. Voter-approved debt, special assessments, direct charges and, in some neighborhoods, a Mello-Roos special tax all add lines. Brentwood has four Community Facilities Districts, so two homes at the same price in different parts of the city can carry noticeably different totals.
The Bottom Line on Brentwood Property Taxes
Contra Costa mails one bill a year by November 1, and if you close after that mailing you will not receive it. Not receiving it does not excuse late penalties.
Then a supplemental bill arrives that your impound account probably does not cover, sometimes more than one. Run the county's estimator during escrow, set the money aside, and read the bill line by line rather than estimating from the purchase price.
Know the number before you commit to it
Buying in Brentwood? Send me an address and I will pull the current bill and tell you what the supplemental is likely to be, before you are in contract rather than after.
See homes for sale in Brentwood
Across 460+ East Bay closings over twenty years, the supplemental bill is the one that generates the most panicked phone calls, always months after closing.
Selling? Your tax profile affects how your home compares to the one down the street.
Find out what your Brentwood home is worth
Or call or text 925-250-9611.
Sources
Contra Costa County, New Property Owners for the annual mailing date, both installment and delinquency dates, and the county's statement that failure to receive a bill does not excuse late penalties. Contra Costa County, Supplemental Property Taxes for how supplemental assessments are triggered and the Supplemental Estimator. Mello-Roos district count from the City of Brentwood.
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 legal, tax or financial advice. Tax procedures, dates and amounts change and vary by property. Confirm everything with the Contra Costa County Treasurer-Tax Collector and Assessor for your specific parcel, and consult your own CPA where appropriate.