Contra Costa County, CA Property Tax: $6,903/yr (2026)
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The effective property tax rate in Contra Costa County is 0.83% of assessed home value. On a home at the county median value of $830,800, that works out to about $6,896 per year, or $575 per month. Contra Costa County is located in central California, and is home to approximately 1,161,458 residents.
About Contra Costa County
Contra Costa County covers approximately 716.9 square miles in California. The county is home to about 1,161,458 residents living in roughly 426,585 housing units, of which 65.3% are owner-occupied. The median household income is $125,727, and the median home was built in 1978.
Contra Costa County borders Alameda County, Marin County, Sacramento County, San Francisco County, San Joaquin County — useful comparisons if you're considering nearby areas with potentially different tax rates.
How Property Taxes Work in California
Property taxes in California are administered at the county level. Each county sets a millage rate applied to the assessed value of real property — the effective rate above accounts for any partial assessments and exemptions already built into the local tax base. Assessed value can differ meaningfully from current market value depending on how often the county reassesses and what fraction of market value it uses.
Most counties in California offer exemptions that reduce the taxable assessed value: homestead exemptions for primary residences, senior exemptions, disability exemptions, and veteran exemptions are common. These reduce your effective rate below the county-wide average shown here. Contact the Contra Costa County Assessor's office to learn which exemptions apply to your property and when to file.
Contra Costa County vs. Neighboring Counties
| Location | Eff. Rate | Median Home | Annual Tax |
|---|---|---|---|
| Contra Costa County, CA | 0.83% | $830,800 | $6,896 |
| California state average | 0.71% | — | $5,899* |
| Alameda County | 0.76% | $1,057,400 | $8,061 |
| Marin County | 0.72% | $1,390,000 | $10,001 |
| Sacramento County | 0.76% | $498,900 | $3,768 |
| San Francisco County | 0.68% | $1,380,500 | $9,412 |
| San Joaquin County | 0.76% | $494,500 | $3,782 |
| US national average | 1.10% | $281,900 | $3,101 |
*State average annual tax computed at Contra Costa County's median home value of $830,800. Source: US Census ACS 2023 5-year estimates.
Frequently Asked Questions
How does Contra Costa County's property tax rate compare to the rest of California?
At 0.83%, Contra Costa County is higher than the California state average of 0.71%. On a home at the county median of $830,800, that means about $6,896 per year — versus $5,899 at the state average rate, a difference of $997 per year. Compared to the national average of 1.10%, Contra Costa County is below average.
What's a typical annual property tax bill in Contra Costa County?
For a home at the county median value of $830,800, the annual property tax in Contra Costa County is approximately $6,896 — or about $575 per month. For a home worth $1,246,200, expect around $10,343 per year. For a $1,661,600 home, approximately $13,791 per year. Use the calculator above to estimate taxes for any assessed value.
Where do I appeal a Contra Costa County property tax assessment?
Property assessment appeals in Contra Costa County are handled by the Contra Costa County Assessor's office. Most jurisdictions require filing within 30–90 days of receiving your assessment notice — confirm the specific deadline with the assessor's office before submitting, as deadlines and procedures vary by county. A successful appeal can reduce your assessed value and lower your tax bill for the current and future tax years.
What exemptions are available in Contra Costa County?
California counties commonly offer homestead exemptions for owner-occupied primary residences, senior citizen exemptions for qualifying homeowners aged 65 and older, exemptions for disabled residents, and veterans' exemptions. Each exemption reduces your assessed taxable value, which in turn reduces your effective tax rate below the county-wide 0.83% shown here. Contact the Contra Costa County Assessor's office to confirm which exemptions are available and the application deadlines.
Data sources: US Census Bureau ACS 2023 5-Year Estimates, US Census Gazetteer (2024), County Adjacency File