Contra Costa County Property Tax
The average property-tax rate in Contra Costa County is about 1.15% of assessed value (Board of Equalization county average, 2024-25) — the 1% Proposition 13 base levy plus each area's voter-approved debt. That's above the statewide average of about 1.11%, making it the 14th-highest of California's 58 counties (the 45th-lowest). On a $500,000 assessed value that's roughly $5,755 a year. Estimate your own bill below, or jump to due dates & where to pay or Contra Costa property tax by city (rates and typical bills).
Contra Costa County property tax: the short answers
- Due dates (2026–27). First installment due Sunday, November 1, 2026, pay by 5 p.m. Thursday, December 10, 2026; second due Monday, February 1, 2027, pay by 5 p.m. Monday, April 12, 2027 (April 10 is a Saturday). Contra Costa County has not published a 2026–27 mailing date; bills must go out by November 1 (§2610.5).
- Where to pay. Online at taxcolp.cccttc.us (search by parcel number or address). No bill yet? Call (925) 608-9500 for a duplicate; a missing bill does not excuse a late payment (§2610.5).
- Typical bill. The county's average single-family home is assessed at about $693,041 (Board of Equalization, 2025), which at the 1.151% county average comes to about $7,977 a year before Mello-Roos and direct charges. A new buyer pays on the purchase price instead.
- Your rate depends on where you are. Across Contra Costa County's 1,114 Tax Rate Areas the ad-valorem rate runs from 1.05% to 1.42% (2025/2026 rate book); see what is in your rate, or the rate by ZIP code.
- Look up a parcel. Contra Costa County Assessor for assessed value and exemptions; the tax collector's portal above for the bill itself.
How Contra Costa County property tax is calculated
California taxes property under Proposition 13: your assessed value is generally set when you buy, then rises no more than 2% a year until the property changes hands or is newly built. The annual bill is that assessed value times the ad-valorem rate — the 1% base plus voter-approved bonds — which is why Contra Costa County's average works out to about 1.15%. Because the bonds differ by Tax Rate Area, two homes in the same county can pay slightly different rates.
What's on a property tax bill
Ad-valorem tax (1% base + voter-approved debt) · Mello-Roos special taxes, where a parcel is in a Community Facilities District (how long they last) · fixed direct assessments (lighting, sewer, etc.). Only the first is value-based; the 1.15% rate covers that part.
Learn the rules behind the rate: how California property tax is calculated, Proposition 13, Mello-Roos, and what triggers a reassessment.
Want your exact rate, not the county average? See what's in your Contra Costa County property tax → — browse by city and Tax Rate Area, or look up your parcel, for the itemized ad-valorem breakdown.
The 1.15% figure is a county average; the actual ad-valorem rate differs by Tax Rate Area. See the Contra Costa County property tax rate by ZIP code → for the typical rate, home value, and bill in each ZIP.
Some Contra Costa County communities also pay a Mello-Roos special tax — see the Contra Costa County CFD district list → with each district's bond debt and delinquency.
Contra Costa County property tax by the numbers
How much is property tax in Contra Costa County? For an existing owner the average single-family home is assessed near $693,041, so at the county's 1.151% average rate (Board of Equalization county average, 2024-25) the implied bill is about $7,977 a year (a mean across all existing owners, not a median). A new buyer is taxed on the purchase price instead — use the calculator above. The figures below are the county-level activity behind that rate.
Sources: California State Board of Equalization (assessors' workload tables, Table E1 single-family values, property-tax allocation), the California Debt and Investment Advisory Commission (Mello-Roos roster), the California FAIR Plan Association (policies in force by county) and CAL FIRE / OSFM fire hazard severity zones weighted by 2020 housing units. County aggregates only, no parcel or owner identities; counts are filings processed and can lag the event year. Verify with the Contra Costa County Assessor before relying on them.
Due dates & where to pay
Contra Costa County property taxes are paid in two installments: first due November 1 (delinquent after December 10) and second due February 1 (delinquent after April 10). A 10% penalty applies after each delinquency date, and a bill still unpaid on July 1 becomes tax-defaulted; after five years in default the county may sell it at auction (see the California tax sale calendar). Boats, aircraft and business equipment are billed separately on the unsecured roll, due in one payment by August 31. Pay or look up a parcel through the Contra Costa County Treasurer-Tax Collector. Portal links, fees and missing-bill numbers for every county are on one look-up-and-pay page.
These deadlines are set by California state law (Revenue & Taxation Code §§ 2605, 2606, 2617 and 2701) and are the same in every county — this is general education, not a county-by-county check. If a delinquency date falls on a weekend or legal holiday, it moves to the next business day. Always confirm the exact dates and amounts on your own tax bill and your county tax collector's website. See the full California property tax due-date calendar for the dated 2026–27 schedule, penalties, and when bills are mailed.
Ways to lower your bill
- The $7,000 Homeowners' Exemption for owner-occupants (~$70/yr) — not the same as the homestead exemption, which protects home equity from creditors and changes no tax.
- Senior programs — Property Tax Postponement (62+, income-qualified; the state pays the bill at 5% simple interest) and a Proposition 19 base-year transfer (55+).
- A Proposition 8 decline-in-value review if the market drops below your assessed value.
- Appealing your assessment if it looks too high — the regular filing window in Contra Costa County runs July 2 to November 30 (2026); only the assessed value can be appealed, not the rate or the flat charges.
Selling in Contra Costa County: the transfer tax
A sale also pays a one-time documentary transfer tax of $1.10 per $1,000 of the price (net of any loan the buyer takes over) to the county (Revenue and Taxation Code §11911), $1,100 on a $1,000,000 sale. In Contra Costa County, El Cerrito, Richmond add their own city transfer taxes on top. Estimate it for any sale with the California transfer tax calculator; the documentary transfer tax guide covers who pays and the exemptions.
Contra Costa County property tax by city
Typical ad-valorem rate, assessed value and annual bill for the largest Contra Costa County cities. Each city page has its own calculator and ZIP-level detail.
The city values are medians of single-family homes — the middle home in each city, while the county's average single-family value shown above ($693,041) is a mean across every single-family parcel in the county. A city can sit above or below that figure — the county average also includes the cities not listed here and the unincorporated areas, and the two come from different rolls (the county parcel file vs. BOE Table E1) — so the mean describes the county as a whole, not a typical home in any one city.
| City | Typical rate (most areas) | Median single-family value | Typical bill | Single-family parcels |
|---|---|---|---|---|
| Antioch | 1.12%most areas 1.05–1.12% | $446,201 | $4,997 | 29,925 |
| Concord | 1.10% | $524,279 | $5,767 | 27,826 |
| San Ramon | 1.08% | $1,123,499 | $12,134 | 18,918 |
| Walnut Creek | 1.09%most areas 1.09–1.10% | $920,897 | $10,038 | 15,929 |
Rate = the middle (median) ad-valorem rate among the city's parcels, each at its own Tax Rate Area (county Auditor-Controller); "most areas" is the 10th–90th percentile range where it varies. Excludes Mello-Roos and fixed direct assessments. Assessed value = the median assessed value of the city's single-family parcels (county Assessor use codes) on the county roll for existing owners — a Proposition 13 basis, not a sale price. Typical bill = that value × the median rate: an illustrative figure for a middle-of-the-road parcel, not the median of actual bills; your bill depends on your own assessed value and Tax Rate Area. Single-family parcels = the parcels behind each median (county Assessor use codes). County aggregates only; verify with the county Assessor before relying on them.
Other Contra Costa County cities (typical total rate in each city's most common Tax Rate Area): Richmond 1.42%, Brentwood 1.10%, Danville 1.08%, Pittsburg 1.15%, Martinez 1.17%, Oakley 1.09%, Pleasant Hill 1.12%, San Pablo 1.28%, Lafayette 1.09%, Hercules 1.28%, El Cerrito 1.28%, Orinda 1.14%. Browse every city's Tax Rate Areas and their itemized bonds on what's in your Contra Costa County property tax.
Neighboring counties' property tax rates
Contra Costa County averages about 1.15%. Of the 6 counties that border it, 2 average less, 4 more:
Frequently Asked Questions
What is the property tax rate in Contra Costa County?
Contra Costa County's average property tax rate is about 1.15% of assessed value (California Board of Equalization, 2024-25) — the 1% Proposition 13 base levy plus each area's voter-approved debt. That's above the statewide average of about 1.11%. Your parcel's exact rate depends on its Tax Rate Area; Mello-Roos and fixed direct assessments, where they apply, are billed on top.
How much is property tax in Contra Costa County?
Multiply your assessed value by about 1.15%. On a $500,000 assessed value that's roughly $5,755 a year. The county's average single-family assessed value is about $693,041 (Board of Equalization, 2025), which at the county's 1.151% average rate (BOE county average, 2024-25) works out to an implied bill near $7,977 a year for an existing owner. Under Proposition 13 your assessed value is generally what you paid when you bought, rising no more than 2% a year — use the calculator above for your own number.
When are Contra Costa County property taxes due?
For 2026–27: the first installment is due Sunday, November 1, 2026 and must be paid by 5 p.m. Thursday, December 10, 2026; the second is due Monday, February 1, 2027 and must be paid by 5 p.m. Monday, April 12, 2027 (April 10 falls on a Saturday). Contra Costa County had not published a 2026–27 mailing date when we last checked; every county must mail or e-mail the annual bill by November 1 (Revenue and Taxation Code §2610.5). The first installment is due November 1 and delinquent after December 10; the second is due February 1 and delinquent after April 10. A 10% penalty applies after each delinquency date. These deadlines are set by California state law (Revenue & Taxation Code §§2605–2606 and §§2617–2619) and are the same in every county; confirm the exact dates on your bill and the county tax collector's website.
How do I look up or pay my Contra Costa County property tax?
Look up and pay on the Contra Costa County Treasurer-Tax Collector's portal at taxcolp.cccttc.us — search by Assessor's Parcel Number (APN, printed on any prior bill) or, on most portals, by address; it shows both installments, penalties and payment history. The portal shows any e-check or card fee before you confirm. If your bill has not arrived, call (925) 608-9500 for a duplicate — not receiving a bill does not excuse a late payment (Revenue and Taxation Code §2610.5). The county has not announced a 2026–27 mailing date; by law bills go out by November 1. Every county's portal, fees and missing-bill number are on one page: californiapropertytools.com/california-property-tax-lookup-and-pay/#contra-costa.
How can I lower my Contra Costa County property tax?
Claim the $7,000 Homeowners' Exemption if you occupy the home; check the senior Property Tax Postponement and, if you're 55+, a Proposition 19 base-year transfer; if the market has fallen below your assessed value, request a Proposition 8 decline-in-value review; and appeal your assessment if it looks too high.
Official Contra Costa County offices
Look up your parcel, exact rate, and bill directly with the county:
- Contra Costa County Assessor — assessed value, exemptions, and parcel records.
- Contra Costa County Auditor-Controller — the tax-rate book and Tax Rate Areas.
- Contra Costa County Treasurer-Tax Collector — pay your bill and look up amounts due.
- Contra Costa County GIS / parcel data — maps and downloadable parcel layers.
Learn More
Rate source: California State Board of Equalization county-average property tax rate (2024-25) — total ad-valorem levies divided by net assessed value. This is a county average; your parcel's rate depends on its Tax Rate Area, and Mello-Roos or fixed direct assessments are extra. Educational estimate, not an official bill — confirm figures with the Contra Costa County Assessor and Treasurer-Tax Collector.