Contra Costa County Property Tax Calculator (2026)
The Contra Costa County median effective property tax rate is 0.78% for 2026 (U.S. Census Bureau ACS 2024), 0.08% above the California median of 0.7%. On a $400,000 home that is about $3,120 a year (~$260 a month). Contra Costa County property is assessed by the Contra Costa County Assessor. Enter your home value below for an instant estimate.
What is the Contra Costa County property tax rate in 2026?
Contra Costa County's median effective property tax rate is 0.78% (U.S. Census Bureau ACS 2024). The county median home is $866,800 with a median tax of about $7,156.
How much is property tax on a $400,000 home in Contra Costa County?
About $3,120 a year, or roughly $260 a month, at the 0.78% median effective rate before exemptions.
Who handles property tax in Contra Costa County?
The Contra Costa County Assessor sets your assessed value. The Contra Costa County Treasurer-Tax Collector collects the bill. Appeal by File a regular assessment appeal between July 2 and November 30; supplemental or escape assessments within 60 days.
When are Contra Costa County property taxes due?
Two installments: the first is due November 1 (delinquent after December 10) and the second is due February 1 (delinquent after April 10).
Contra Costa County Property Tax Calculator (2026)
Rates updated 2026 (U.S. Census Bureau ACS 2024). Live estimate — county median effective rate.
Contra Costa County's median effective property tax rate is 0.08% above the California median and the US average is 0.94%. Your assessed value, local millage, and exemptions (homestead, senior, veteran) will change the actual bill.
Who assesses and collects property tax in Contra Costa County?
In Contra Costa County, the Contra Costa County Assessor sets the assessed value of your home each year. The Contra Costa County Treasurer-Tax Collector issues the bill and collects payment. Assessment appeals are heard by the Contra Costa County Assessment Appeals Board.
For your exact rate, exemptions, and account details, go to contracosta.ca.gov — the official source for Contra Costa County. This page is an independent estimate, not a tax bill.
How much is property tax on a home in Contra Costa County?
At the Contra Costa County median effective rate of 0.78%, here is the estimated annual and monthly bill by home value. The county median home value is $866,800, with a median tax of about $7,156 a year.
| Home value | Rate (0.78%) | Annual tax | Monthly |
|---|---|---|---|
| $200,000 | 0.78% | $1,560 | $130 |
| $400,000 | 0.78% | $3,120 | $260 |
| $866,800 (county median) | 0.78% | $7,156 | $596 |
| $750,000 | 0.78% | $5,850 | $488 |
When are Contra Costa County property taxes due, and when can you appeal?
Assessment (lien) date: January 1 (lien date); reassessed on a change of ownership or new construction under Proposition 13. Proposition 13 — assessed value is the purchase price plus up to 2% inflation per year, reset only on sale or new construction.
Payment: Two installments: the first is due November 1 (delinquent after December 10) and the second is due February 1 (delinquent after April 10).
Appeal window: File a regular assessment appeal between July 2 and November 30; supplemental or escape assessments within 60 days. Missing it usually means accepting the assessed value for the year.
What exemptions can lower your Contra Costa County property tax?
| Exemption | Amount or rule |
|---|---|
| Homeowners' Exemption | $7,000 off assessed value (about $70/year); file by February 15 for the full amount, late claims get $5,600 |
| Disabled Veterans' Exemption | exempts a large share of assessed value for qualifying disabled veterans and surviving spouses |
| Proposition 19 base-value transfer | owners 55+, disabled, or disaster victims can move their Prop 13 base value to a replacement home |
Amounts and eligibility change over time and are administered locally, so confirm what you qualify for with the Contra Costa County Assessor before relying on a figure.
How do you estimate your Contra Costa County property tax by hand?
- Find your home's assessed value on your latest notice from the Contra Costa County Assessor.
- Subtract any exemptions you qualify for, such as homestead, senior, or veteran relief.
- Multiply the remaining taxable value by your local combined tax rate.
- For a quick estimate, multiply your home value by 0.78% — the Contra Costa County median effective rate used above.
Which cities are in Contra Costa County, and what makes it different?
Contra Costa County includes Concord, Richmond, Antioch, Walnut Creek, San Ramon, Pittsburg, Brentwood, Danville, Martinez, among others. Rates differ between these cities and their school and special districts, so two homes of equal value can owe different amounts.
Contra Costa County (the East Bay, county seat Martinez) reassesses to market value only on a sale or new construction under Proposition 13. The regular appeal window runs through November 30, and many master-planned communities carry Mello-Roos special-district charges that add to the base 1% rate.