This page helps users handle a Property Tax need in Contra Costa County, California, including tax bill lookup, payment timing, fees, and office contact options.
The main public channel is the Contra Costa County Treasurer and Tax Collector Tax Lookup, supported by the Treasurer-Tax Collector’s Office for secured property tax billing and payment questions.
Contra Costa County Treasurer and Tax Collector Tax Lookup
Use the county tax portal to look up a property tax account, review installment options, and check the balance due shown by the Treasurer and Tax Collector.
- Property tax account information
- Installment selection for the bill shown in the portal
After you find the account, review the displayed balance carefully because pending payments or corrections may affect accuracy. Posting occurs at least weekly.
- Open the Treasurer and Tax Collector tax lookup.
- Search for the property tax account.
- Review the installments, balance due, penalties, and cart total before payment.
- Choose a payment type and confirm any service fee before submitting.
Pay early when possible. The Tax Collector’s Office warns that website availability is not guaranteed, and delinquent fees or penalties may result if a payment is delayed.
Secured property tax billing and due dates
The Tax Collector mails secured tax bills by November 1. Annual tax bills are mailed once a year in late September through early October and include stubs for both installments.
| Tax bill item | Timing | Penalty rule |
|---|---|---|
| Secured tax bill mailing | By November 1 | Failure to receive a bill does not remove the tax lien or stop penalties. |
| First installment | Payable by November 1 and delinquent after December 10 | A 10% penalty applies after the deadline. |
| Second installment | Payable by February 1 and delinquent after April 10 | A 10% penalty plus a $20 delinquent cost applies after the deadline. |
| Tax-default date | If unpaid by 5:00 p.m. on June 30, the property becomes tax-defaulted on July 1 | A $15 redemption fee and monthly interest of 1.5% are added to unpaid taxes. |
If a delinquency date falls on a weekend or holiday, the deadline extends to the next business day. In-person payments must be made by 5:00 p.m.; electronic payments must be made by midnight on the delinquency date.
Ways to pay secured property taxes
Contra Costa County offers online, in-person, phone, and mail payment options for secured property taxes. The county’s payment information page explains the available methods for choosing the option that fits your situation.
Current property tax payments must be made in full. Delinquent taxes may be paid in installments, and payment questions route through the Treasurer-Tax Collector.
Review the county’s secured property tax payment options before choosing a payment method.
Online payment service fees
Service fees depend on the payment type selected in the tax portal.
| Payment type | Service fee | Important note |
|---|---|---|
| E-check | No service fee | Rejected e-checks may be subject to the county returned check fee of up to $85. |
| PayPal | 2.50% of the transaction amount, with a $3.50 minimum | The fee is added to the selected tax payment amount. |
| Credit card or debit card | 2.50% of the transaction amount, with a $3.50 minimum | The fee is added to the selected tax payment amount. |
Paperless billing and due date reminders
The Tax Collector’s Office offers free secured property tax bill notifications by email. After signing up, users add parcel numbers to the APN list and receive the annual email notification in September.
Paperless billing links to the online tax bill so users can view, print, and pay installments online. The office also sends reminder notifications before each installment delinquent date.
Users who only need reminders may use the Due Date E-Mail Reminder service. A reminder is sent about two weeks before each delinquent date, and up to three parcel numbers can be included per reminder account.
Use the county’s paperless billing information or due date email reminder service to review these options.
Email reminders do not remove the taxpayer’s responsibility to pay on time, and penalties still apply to delinquent payments.
Supplemental bills, refunds, and assessment questions
Property tax bills can be affected by value changes, ownership changes, new construction, overpayments, and assessment corrections.
Supplemental bills are issued when state law requires the Assessor to reappraise property after a change in ownership or completion of new construction. Supplemental bills and refunds are generated approximately 60 days from the date listed on the supplemental notification.
Refunds are commonly tied to reductions in assessed value by the Assessor’s Office. A duplicate payment refund is generated approximately 60 days from the date the Tax Collector’s Office posted the initial payment.
For valuation and assessment questions, the Contra Costa County Assessor’s Office handles assessment duties. For payment posting, duplicate payment refund timing, and tax bill payment questions, contact the Treasurer-Tax Collector.
Property tax postponement for eligible California homeowners
The California State Controller’s Property Tax Postponement Program allows eligible homeowners who are seniors, are blind, or have a disability to defer current-year property taxes on their principal residence.
Eligibility criteria include at least 40 percent equity in the home and an annual household income of $55,181 or less, among other requirements. The deferred taxes are secured by a lien against the property and must be repaid.
The 2025-26 program timeline lists applications available in September 2025, the filing period opening October 1, 2025, and the filing period closing February 10, 2026. Review the State Controller’s Property Tax Postponement program for program details.
Contra Costa County property tax contacts
Use these contacts for property tax payment, billing, assessment, and postponement questions.
- Contra Costa County Treasurer-Tax Collector, Finance Building, 625 Court Street, Room 100, Martinez, CA 94553. Mailing address: Contra Costa County Treasurer-Tax Collector, P.O. Box 631, Martinez, CA 94553. Phone: (925) 608-9500. Fax: (925) 608-9598. Email: TaxInfo@tax.cccounty.us. Walk-in hours: Mon–Fri 8:00 a.m. – 5:00 p.m. Call Center & Chat: Mon–Fri 8:00 a.m. – 4:00 p.m. TTY: Call 711.
- Contra Costa County Assessor’s Office, 2530 Arnold Dr, Suite 100, Martinez, CA 94553. Phone: (925) 313-7400. Fax: (925) 313-7488. Office hours: Monday through Friday 8:00am to 4:00pm. Phone hours: Monday through Friday 8:00am to 4:00pm. TTY: Call 711.
- California State Controller’s Property Tax Postponement Program. Phone: (800) 952-5661. Email: postponement@sco.ca.gov.
Common questions
Where can I look up a Contra Costa County property tax bill?
Use the Treasurer and Tax Collector’s property tax account lookup to review account and installment information.
What if I did not receive my secured property tax bill?
You can request a duplicate tax bill by calling the Tax Collector at (925) 608-9500 or by using the tax portal to view the amount due. Not receiving a bill does not prevent penalties.
Are partial payments accepted for current property taxes?
No. Current property tax payments must be made in full. Delinquent taxes may be paid in installments.
When do secured property taxes become delinquent?
The first installment is delinquent after December 10. The second installment is delinquent after April 10. If a delinquency date falls on a weekend or holiday, the deadline extends to the next business day.
Which office handles property value or assessment questions?
The Contra Costa County Assessor’s Office handles assessment duties, including valuing real property and maintaining assessment maps. Contact the Assessor for assessment questions and the Treasurer-Tax Collector for payment questions.