Contra Costa County · Bay Area · 2026-27
Contra Costa County property tax
Levy rate
1.24%
Varies by tax rate area
Median sale price
—
Redfin, live
Population
1.2M
State projection
Appeal window
July 2
through November 30
Estimate for a Contra Costa County home
Estimated annual tax
$12,313
$1,026 a month · 1.23% effective
Mello-Roos, parcel taxes and direct assessments are billed on top of this and are not included. Your assessed value is what you paid, factored each year — not what the home is worth today.
How Contra Costa County compares
At 1.24%, Contra Costa has the 4th highest levy rate of California’s 58 counties. The state median is 1.12%, so a home here is charged 0.12 percentage points above the middle of the state.
On the $1,000,000 home above, that difference is worth about $1,250 a year more than what the same home would cost in a median-rate county.
Across the 9 counties of Bay Area, levy rates run from 1.11% to 1.26%. Contra Costa sits at the middle of that band.
What Proposition 13 does here
The levy rate is 1.24%, but across every property on the county roll the tax actually collected comes to about 0.78% of market value. That gap of 0.46 percentage points is Proposition 13 measured across the whole county: most owners are assessed on what they paid years ago, not on what their home is worth now.
Buying resets your assessment to the purchase price, which is why a new owner pays closer to the full levy rate than their neighbours do.
If your assessment looks too high
Proposition 8 requires the assessor to enrol the LOWER of your factored base year value and your home’s current market value. If the market has fallen below what you are assessed at, you are entitled to a temporary reduction — but it is not always applied automatically, so you may have to ask.
In Contra Costa County the window runs July 2 to November 30. Bring recent comparable sales from around 1 January — that is the lien date your assessment is measured against, not the date you file.
Appealing your assessment
Filing opens July 2 and closes November 30 in Contra Costa County, along with most of California. Eleven counties close on 15 September instead; this is not one of them.
The Board of Equalization re-issues the list of September counties each year, so confirm with your clerk of the board before relying on either date. Filing fees differ by county; many charge nothing.
Instalments are due 1 November and 1 February, and become delinquent after 10 December and 10 April.