2026 Property Tax Due Dates
December 10
First installment
April 10
Second installment
Payment Methods
Online, Mail, In-Person
Contra Costa County Treasurer
Phone
(925) 608-9500Office Hours
How to Pay
Online
Pay using credit card or e-check
By Mail
Mail check payable to Contra Costa County Treasurer
In Person
Visit the Treasurer's office — 625 Court St, Room 100, Martinez CA 94553, Mon-Fri 8am - 5pm
About Property Taxes in California
California property taxes are governed by Proposition 13, passed in 1978, which fundamentally shaped how property is assessed in the state. Under Prop 13, property is assessed at its purchase price (fair market value at time of sale), and annual increases in assessed value are capped at 2% per year or the rate of inflation, whichever is lower. Long-term homeowners often pay taxes on a fraction of their home's current market value. Property taxes in California are administered at the county level. The county assessor determines property values, the county auditor-controller calculates the tax amounts, and the county tax collector bills and collects. Tax rates are set at 1% of assessed value by Proposition 13, plus additional voter-approved bonds and assessments that typically bring the total to 1.1–1.6% depending on location.
Payment & Assessment
California property taxes are split into two equal installments: First installment: Due November 1, delinquent after December 10 (10% penalty) Second installment: Due February 1, delinquent after April 10 (10% penalty + $10 cost) If a delinquency date falls on a weekend or holiday, the deadline extends to the next business day. A useful rule of thumb: if you pay by December 10, you are fine for the first half; if you pay by April 10, you are fine for the second half. Most counties offer online payment through the county tax collector's website. You can also pay by mail (must be postmarked by the deadline), in person, or by phone. Note: Supplemental tax bills are issued separately when property changes ownership or new construction is completed. These are in addition to your regular annual tax bill and are due approximately 30 days after the bill date.
Statewide framework for California. Your county's specific rates and deadlines are shown above.
Other Counties in California
About Contra Costa County
Contra Costa County is a county located in the U.S. state of California, in the East Bay of the San Francisco Bay Area. As of the 2020 United States census, the population was 1,165,927. The county seat is Martinez. It occupies the northern portion of the East Bay region of the San Francisco Bay Area and is primarily suburban. The county's name refers to its position on the other side of the bay from San Francisco. Contra Costa County is included in the San Francisco–Oakland–Berkeley, CA Metropolitan Statistical Area.
Source: Wikipedia — content available under CC BY-SA 4.0
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Due dates shown are for reference only. Contact your county treasurer's office to confirm official deadlines before making payments.