Estimate Your Annual Property Tax in Contra Costa County, California
Estimate your Contra Costa County property tax for the 2026-27 tax year using assessed value, local tax-rate context, exemptions, and parcel-specific charges. This calculator is built for Contra Costa County areas such as Antioch, Concord, Richmond, Walnut Creek, San Ramon, Brentwood, Martinez, Lafayette, Danville, and other East Bay areas, where TRA assignments and direct charges can differ by parcel.
Contra Costa County Property Tax Calculator
Estimated annual property tax
$0Taxable assessed value
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Ad valorem tax
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Direct charges
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Monthly estimate
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Two installment estimate
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Projected next-year assessed value
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- 21 Local Areas
- August 2026 Updated
- No Signup Required
- Annual + Monthly Estimates
Contra Costa CA Property Tax Due Dates 2026-27
Contra Costa County secured property taxes follow California’s two-installment schedule. The first installment is due November 1, and the second installment is due February 1. The key delinquency dates for avoiding penalties are December 10 and April 10.
First Installment
November 1, 2026 is the due date for the first secured property-tax installment.
First Installment Delinquent
December 10, 2026 is the last day to pay the first installment without penalty.
Second Installment
February 1, 2027 is the due date for the second secured property-tax installment.
Second Installment Delinquent
April 10, 2027 is the statutory delinquency date; because it falls Saturday, confirm county handling.
Important: Property owners should confirm payment instructions, parcel balance, postmark rules, and weekend or holiday deadline treatment with the Contra Costa County Treasurer-Tax Collector or official county tax authority.
Contra Costa County Property Tax Penalties
Late property-tax payments in Contra Costa County can add penalties and costs to the amount due. Because each installment has its own delinquency date, taxpayers should monitor payment status before the deadline and verify any parcel-specific balance with official county records.
What Happens If You Miss a Payment?
For 2026-27, the first installment becomes delinquent after December 10, 2026 at 5 p.m. or close of business, whichever is later, and a 10% penalty generally applies. The second installment is tied to April 10, 2027; because that date falls on Saturday, confirm the next-business-day deadline. Late second installments generally include a 10% penalty plus applicable statutory county costs, with additional default penalties possible after June 30.
Important Reminder for Property Owners
Contra Costa County payment records and official tax tools should be checked for exact parcel balances and costs. Keep payment confirmations, tax bill numbers, and parcel details handy, especially when mailing payments or using online systems near the deadline.
Explore More Contra Costa County Property Resources
Use these Contra Costa County property resources when you need more than an estimate. They can help you review assessment details, compare local tax-rate assumptions, estimate transfer-related costs, and understand how exemptions, direct charges, and special assessments affect a final bill.
Property Search
Search Contra Costa County property records by available parcel, owner, address, or assessment details through official property tools.
Tax Rates
Review Contra Costa County tax-rate context for local cities, communities, districts, and unincorporated areas.
Document Stamp Calculator
Estimate California documentary transfer tax or recording-related transfer costs when a taxable real estate transfer applies.
Property Guide
Explore Contra Costa County property guidance covering assessment records, ownership changes, tax bills, and local property research.
How to Calculate Your Contra Costa County Property Tax
Start with the assessed value, choose the closest Contra Costa County local area, and add known exemptions, assessments, or direct charges from the tax bill. The calculator provides a planning estimate, not an official tax bill from the county.
Step 1
Enter the assessed value used for taxation before exemptions, local charges, or special assessments are added.
Step 2
Select a representative city, community, district, or unincorporated area from the local-area dropdown.
Step 3
Enter the exact TRA rate if your parcel's official tax-rate area is known from county or BOE records.
Step 4
Apply the homeowner exemption if the property is owned and occupied as a qualifying principal residence.
Step 5
Add special assessments or fixed charges that appear separately on the Contra Costa County tax bill.
Step 6
Include Mello-Roos or CFD charges if the parcel is inside a community facilities district.
Step 7
Enter parcel taxes or direct local charges tied to schools, services, districts, or voter-approved obligations.
Step 8
Use a projected assessed-value increase for planning, while actual changes remain governed by California assessment law.
Step 9
Click Calculate Tax to combine taxable value, rate, exemptions, and charges into an estimated property-tax result.
Contra Costa County Property Tax Calculation Formula
Property Tax Estimate = ((Assessed Value – Eligible Exemption) x Applicable Tax Rate) + Voter-Approved Debt + Special Assessments + Fixed Charges + Mello-Roos/CFD Charges + Parcel Taxes or Other Direct Charges
For example: If a taxable Contra Costa County value is $725,000 and the selected local rate is 1.1210%, the ad valorem estimate is about $8,127 before parcel-specific bonds, direct charges, or assessments are added.
Visit Other California County Property Tax Calculators
Property-tax estimates should be county-specific because California parcels are assigned to tax-rate areas with different schools, districts, bonds, and direct assessments. Neighboring counties can share statewide rules while producing very different local tax bills.
Alameda County
Sacramento County
Sacramento County
San Joaquin County
Marin County
San Francisco County
Pros
- Quick Tax Estimates
- Assessed Value Input
- Area-Based Tax Rates
- Custom Tax Rate
- Homeowner Exemption
- Special Assessments
- Mello-Roos Charges
- Local Parcel Charges
- Monthly & Installment Estimates
- Projected Property Value
Cons
- Estimate Only
- No Parcel-Specific
- Exact TRA Required
- Exemption Eligibility
- Local Tax Variations
FAQ's
Why can Contra Costa County properties in nearby areas have different tax bills?
A Walnut Creek parcel can differ from one in Richmond, Antioch, or San Ramon because local bonds, TRA assignments, and direct charges can vary.
How does Proposition 13 affect Contra Costa County assessed value?
California Proposition 13 generally limits annual assessed-value increases unless a reassessment event occurs. A purchase, ownership change, or assessable new construction can create a new base value.
Can a home purchase create a supplemental tax bill in Contra Costa County?
Yes. A purchase or ownership change can trigger a supplemental assessment when the new assessed value differs from the prior value. Supplemental bills are separate from the regular secured tax bill.
Does refinancing change my Contra Costa County property tax
Refinancing alone usually does not reassess the property because ownership has not changed. Title transfers or ownership restructuring should be reviewed before assuming there is no assessment effect.
Can improvements increase my Contra Costa County assessment?
Assessable new construction can add value to the tax roll. Repairs and routine maintenance are treated differently, so owners should verify major improvement questions with the county Assessor.
How do exemptions affect the calculator estimate?
A qualifying exemption can reduce the taxable value or tax liability, but eligibility must be verified. The calculator lets users enter exemption information when it applies to the property.
Where can I verify an official Contra Costa County tax balance?
Use the official Contra Costa County Treasurer-Tax Collector payment or bill lookup system, or contact the county directly. Calculator results do not confirm paid, unpaid, or delinquent status.
What should I gather before estimating?
Collect the assessed value, parcel number, tax bill, local area, homeowner exemption status, TRA rate if known, special assessments, and direct charges.
Why might my estimate differ from the official Contra Costa County bill?
The official bill may include parcel-specific bonds, direct assessments, supplemental taxes, prior balances, penalties, corrections, or payment-processing details not captured by general inputs.
Can I appeal a Contra Costa County property assessment?
Property owners who disagree with an assessed value should contact the county Assessor and confirm formal assessment appeal deadlines, forms, evidence requirements, and filing procedures.