Contra Costa County property tax by city: estimated first-year bills
The table estimates a first-year bill in each of the county's busiest markets. It multiplies Redfin's median sale price for the three months to September 2026, less the $7,000 homeowners' exemption, by the BOE's 1.151% county average. It is an illustration, not a quote: your bill uses your tax rate area's exact rate, plus fixed charges and any Mello-Roos tax.
| City | Redfin median sale price (3 months to Sept 2026) | Change from a year earlier | Estimated tax at 1.151% |
|---|---|---|---|
| Richmond | $579,724 | -3.4% | $6,592 |
| Pittsburg | $589,719 | +1.2% | $6,707 |
| Antioch | $592,218 | +1.7% | $6,736 |
| Concord | $719,657 | -2.8% | $8,203 |
| Brentwood | $744,645 | -3.9% | $8,490 |
| Martinez | $819,610 | +5.1% | $9,353 |
| Walnut Creek | $847,596 | -2.0% | $9,675 |
| San Ramon | $1,449,310 | +2.8% | $16,601 |
| Orinda | $1,749,167 | -3.4% | $20,052 |
| Danville | $1,799,143 | +6.6% | $20,628 |
| Lafayette | $1,926,583 | +1.9% | $22,094 |
The price, not the rate, drives most of the gap between cities. A Lafayette buyer at the median pays roughly three times what a Richmond buyer does, even before any difference in bond rates.
Contra Costa tax rate areas and the Detail of Tax Rates
Every Contra Costa parcel sits in a tax rate area (TRA), a code printed on the secured bill. The TRA decides which voter-approved debt is added to the 1% general levy, mainly school and community college bonds and other bonds approved by voters in that area. The Auditor-Controller publishes every TRA's rate each October in the Detail of Tax Rates; the 2025-26 edition is dated October 2025.
Finding your Contra Costa TRA and rate
Look up the parcel on the Treasurer-Tax Collector's Tax Lookup portal, or read the TRA from the bill. Then find the same code in the Detail of Tax Rates and add the lines. If you are buying, ask the listing agent or escrow for the seller's current bill so you see both the rate and the fixed charges.
Why two Contra Costa homes at one price pay different taxes
Two homes bought for the same price in the same year can have different bills because their TRAs differ, because one carries a Mello-Roos or lighting district charge, or because one owner filed the homeowners' exemption and the other did not. The rate is applied to assessed value, so a neighbor who bought years ago will also pay far less.
Contra Costa County's tax base
The BOE puts Contra Costa's net assessed value for the 2025 lien year at $294.8 billion, the tenth largest of the 58 counties. Its 1.151% average rate sits between Sonoma County's 1.139% and Sacramento County's 1.155%.
A worked Contra Costa County property tax bill
This example uses Zillow's typical Contra Costa County home value for September 2026, $768,394, as the purchase price of an owner-occupied home, and the BOE's 1.151% average as a stand-in for the TRA rate.
| Line | Math | Amount |
|---|---|---|
| Assessed value | Purchase price | $768,394 |
| Less homeowners' exemption | $768,394 - $7,000 | $761,394 |
| General levy (1%) | $761,394 x 1.000% | $7,613.94 |
| Voter-approved debt at the county average | $761,394 x 0.151% | $1,149.70 |
| Estimated ad valorem tax | $761,394 x 1.151% | $8,763.64 |
Paid in two installments of about $4,382. Replace 1.151% with your TRA's rate from the Detail of Tax Rates for a real figure, then add the fixed charges listed on the bill.
Year two under Prop 13's 2% cap
If the assessor applies the full 2% factor, the assessed value rises to about $783,762. Less the exemption, the estimated tax at 1.151% is about $8,941.
Prices below the 2022 peak: decline-in-value reviews
Contra Costa is one of the Bay Area counties where values have not recovered their peak. Zillow's typical county home value was $874,801 in June 2022 and $768,394 in September 2026, about 12% lower, and down 3.0% over five years. Redfin's three-month median fell from a year earlier in Concord, Walnut Creek, Brentwood, Richmond, Pleasant Hill, El Cerrito and Hercules.
Who in Contra Costa may benefit from a Prop 8 review
If you bought near the 2022 peak, your factored base year value may now be above what the home would sell for. Proposition 8 lets the Assessor enroll the lower market value for that year. The reduction is temporary: as prices recover, the value can rise again, faster than 2% a year, up to your factored base year value.
How to ask the Contra Costa Assessor for a review
The Assessor's Review Your Value page has request forms by property type. Send recent sales of similar homes close to the January 1 lien date. If the Assessor lowers your value, the value is reviewed again each year as of the January 1 lien date. Call (925) 313-7400 with questions.
Contra Costa County property tax exemptions
Homeowners' exemption in Contra Costa County
File the homeowners' exemption claim with the Contra Costa Assessor's Office after you buy. It takes $7,000 off the assessed value, worth about $81 a year at the 1.151% average. File by February 15 for the full amount; the California property tax guide explains the late-filing rule and the disabled veterans' exemption.
Senior parcel tax exemptions in Contra Costa
Parcel taxes from school districts and other agencies are separate from the rate. Some offer an exemption, often for owners 65 and older, run by the agency that levies the tax. Look for the agency's phone number next to each fixed charge on your bill and apply to that agency directly.
Prop 19 transfers and Contra Costa homeowners
Contra Costa owners who are 55 or older, severely disabled or displaced by a disaster can move their taxable value to a replacement home anywhere in California under Prop 19. A Danville or Lafayette owner who bought decades ago can carry a much lower value to a new home. Inherited homes keep the parent's value only if the child moves in, within a cap. See the Prop 19 guide and file with the Contra Costa Assessor.
Supplemental tax bills after you buy in Contra Costa
A purchase triggers a supplemental assessment for the difference between your price and the old taxable value. The bill comes to you, not the lender.
Example: a Walnut Creek purchase closing March 1
Say you pay Walnut Creek's three-month Redfin median of $847,596 for a home with a prior taxable value of $400,000, closing March 1. The supplemental assessment is $447,596. Because you bought between January 1 and May 31, you get two supplemental bills. The first covers March through June: roughly $447,596 x 1.151% x 4/12 = $1,717. The second covers the whole next fiscal year: roughly $447,596 x 1.151% = $5,152, because that year's regular bill was set on the old value. Use your TRA's rate for a real estimate.
Special taxes and Mello-Roos in Contra Costa
Fixed charges and special taxes appear below the rate on a Contra Costa bill. They can include school parcel taxes, lighting and landscaping districts, sewer service charges and Mello-Roos special taxes from community facilities districts. The county also posts annual rates for its own districts, such as Community Facilities District 2007-1 for stormwater management facilities. Newer subdivisions are the most likely to carry a Mello-Roos tax; check the bill and the district's maximum tax before you buy. The Mello-Roos guide shows how.
Paying Contra Costa County property tax
The first installment is due November 1 and becomes delinquent after December 10. The second is due February 1 and becomes delinquent after April 10. A late installment carries a 10% penalty. The Treasurer-Tax Collector's office is at 625 Court Street, Room 100, Martinez, open 8 a.m. to 5 p.m.; the call center at (925) 608-9500 answers from 8 a.m. to 4 p.m.
Contra Costa payment options and fees
- E-check: no service fee through the Tax Lookup portal. A rejected e-check is charged the county's returned check fee of up to $85.
- Card or PayPal: 2.50% of the payment, minimum $3.50.
- Mail: use the return envelope and payment stub sent with the bill. The office's general mailing address is P.O. Box 631, Martinez, CA 94553-0063.
- In person: 625 Court Street, Room 100, Martinez.
Paying ahead and avoiding late penalties
The Tax Lookup page warns that the site may not always be available and that delinquent penalties can result, so pay early rather than on December 10. The balance shown includes any penalty as of the date stated on the page, and payments are posted at least weekly, so a recent payment may not show yet.
Appealing a Contra Costa County assessment
The State Board of Equalization lists Contra Costa's 2026 regular filing deadline as November 30, 2026; the period opened July 2. Appeals of supplemental or escape assessments are due within 60 days of the notice.
Filing with the Contra Costa Assessment Appeals Board
Applications go to the Assessment Appeals Board at 1025 Escobar Street, 1st Floor, Martinez. The county's appeals page lists a $40 application fee per parcel and tax year; confirm the fee and how to pay it with the Assessment Appeals Clerk at (925) 655-2008 before you file. Try the Assessor's informal review first if the issue is a drop in market value. Keep paying the bill while you wait for a hearing.
See the Contra Costa County data page for current sales figures, and our Walnut Creek, Danville and Lafayette guides for local markets.