Contra Costa County Tax Collector: Pay Taxes & Office Hours
If you are searching for the Contra Costa County Tax Collector in 2026, this guide helps you pay secured property taxes online, search your tax bill by APN, understand December 10 and April 10 delinquency dates, find the Treasurer-Tax Collector office in Martinez, check walk-in and call-center hours, use phone payment, review card and eCheck fees, watch the official payment video, and know when to contact the Assessor instead of the Tax Collector.
The Contra Costa County Treasurer-Tax Collector office is located at Finance Building, 625 Court Street, Room 100, Martinez, CA 94553. The mailing address is Contra Costa County Treasurer-Tax Collector, P.O. Box 631, Martinez, CA 94553. The main phone number is (925) 608-9500, TTY is 711, walk-in hours are listed as Monday-Friday, 8:00 AM-5:00 PM, and call center/chat hours are listed as Monday-Friday, 8:00 AM-4:00 PM, except holidays. Property owners can use the official tax portal to look up property tax details, pay online, schedule payments, sign up for paperless billing and review tax history.
Official source: Contra Costa County Treasurer-Tax Collector, official tax portal, and ways to pay secured property taxes.Contra Costa County Tax Collector: What the Treasurer-Tax Collector Handles
The Contra Costa County Treasurer-Tax Collector bills, collects, safeguards and disburses public monies and properties. For most property owners, the most common tasks are tax bill lookup, online payment, payment scheduling, tax history, paperless billing, and payment questions.
When Is Your
Next Tax Deadline?
Select your state — see your exact deadline, live countdown, and whether you’re on time or already accruing penalties.
Use the Tax Collector when your task is paying a secured property tax bill, checking paid status, scheduling a payment, using phone payment, mailing a check, asking about payment methods, or understanding delinquent penalties. Use the Contra Costa County Assessor when your question is about assessed value, ownership record, mailing address change, exemptions, parcel details, or property characteristics.
Property Tax Penalty & Interest Calculator
State-specific penalty rates • Interest accrual • Tax lien deadline • Cost-of-waiting breakdown
| Original Tax Amount | $0.00 |
| Initial Penalty— | $0.00 |
| Monthly Interest— | $0.00 |
| Fixed Fees— | $0.00 |
| Total Due | $0.00 |
Daily Accrual Rate
Interest and penalties are adding this much to your balance every single day
Tax Lien Warning
| If You Pay On | Days Late | Penalty | Interest | Total Owed | Extra Cost |
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Use Tax Collector for payment
Pay online, pay by phone, pay by mail, schedule payments, review tax history, check current and prior-year tax bills, and handle delinquency payment questions.
Use Assessor for records
Contact the Assessor for mailing address changes, exemptions, assessed value, ownership record questions, and property details that affect the bill.
Use official links before paying
Do not pay from random ads or unofficial bill-pay pages unless you understand the risk. Start with the official county tax portal.
How to Pay Contra Costa County Property Taxes Online
The official Contra Costa County tax portal lets property owners look up property tax details, pay online, schedule payments, sign up for paperless billing and review tax history.
Before paying, verify the APN, property address, owner name, tax year, installment, penalties, and balance. The county warns that website availability is not guaranteed and recommends paying early because delinquent fees and penalties may result from unavailability.
Official source: official tax portal account lookup and ways to pay secured property taxes.Open the official tax portal
Use the Contra Costa County Treasurer-Tax Collector tax portal, not a third-party bill-pay page. Confirm the page shows the county tax portal before entering payment details.
Search by APN or bill information
For secured property taxes, your 10-digit APN is the best lookup key. Match the parcel, property address, tax year and installment before selecting payment.
Choose installment carefully
The first installment is payable November 1 and delinquent after December 10. The second installment is payable February 1 and delinquent after April 10.
Review service fees before payment
Credit card, debit card and online wallet payments have a percentage-based service fee. E-check payments are accepted online with no additional service fee, but rejected e-checks can trigger a returned-check fee.
Save the confirmation number
After paying online or by phone, save the confirmation number, APN, installment, amount, date and payment method. Later, check the portal to confirm posting.
Open tax portal
Use the official portal to view or pay current and previous-year property tax bills, schedule payments, and review tax history.
Open Official PortalWays to pay
Use the county payment-method page to compare online payment, drive-thru drop box, mail, in-person office, phone and payment scheduler options.
View Ways to PayContra Costa County Property Tax Lookup by APN, Bill, Address or Tax History
The official tax portal is the main starting point for tax bill lookup, payment, payment scheduling, tax history and paperless billing. For most secured property tax questions, the APN is the cleanest search path.
| Search need | Best starting point | What to verify before paying |
|---|---|---|
| I have the APN | Use the official tax portal account lookup. | 10-digit APN, tax year, installment, property address and balance. |
| I need tax history | Use the tax portal history/review options. | Paid status, posting date, amount, and installment. |
| I did not receive a bill | Use tax portal or call the Tax Collector. | Bill amount, APN, due date, and penalty status. |
| I need address or exemption help | Assessor, not Tax Collector. | Mailing address, exemption status, assessed value record. |
Searchers often type “Contra Costa County property tax lookup,” “Contra Costa County pay property tax,” “Contra Costa tax collector APN search,” or “Contra Costa tax bill.” These all point to the same practical task: find the correct tax account, verify the installment, and save payment proof.
Official source: Contra Costa County tax portal and secured property tax information.Contra Costa County Tax Collector Office Address, Mailing Address and Contact
The Tax Collector office is at the Finance Building in Martinez. Use the correct office address for walk-in service and the correct P.O. Box for mailed payments.
Walk-In Office
Use for in-person payment and taxpayer service
Mailing Address
Use for mailed tax payments
If submitting a tax payment without a coupon, the county directs payments to County Tax Collector, P.O. Box 631, Martinez, CA 94553-0063. Your canceled check is your receipt, and the county recommends verifying payment posting online by entering the 10-digit APN.
Official source: Contra Costa County pay by mail and Tax Collector contact page.Contra Costa County Tax Collector Office Hours and Best Time to Call
Walk-in hours are listed Monday through Friday, 8:00 AM to 5:00 PM, except holidays. Call center and chat hours are listed Monday through Friday, 8:00 AM to 4:00 PM, except holidays.
Official source: Treasurer-Tax Collector contact details and ways to pay page.Best time to call
Call earlier in the day, especially close to December 10 or April 10. Deadline periods can bring long waits and urgent payment questions.
Before visiting
Bring your bill, APN, payment method, ID if needed, and any confirmation number if you are following up on a payment.
Deadline caution
Do not wait until late afternoon on a delinquency date. In-person payment must be made by 5:00 PM, while electronic payment has a midnight deadline for secured installments.
Contra Costa County Property Tax Payment Fees and Accepted Payment Methods
Contra Costa County lists multiple payment methods, including tax portal, drive-thru drop box, mail, in-person office, phone payment, payment scheduler, PTOPS for owners of 10 or more properties, and electronic funds transfer for payments over $50,000.
Accepted payment methods include major credit cards with a 2.5% fee and $3.50 minimum, online payment services such as Apple Pay, Google Pay, Venmo and PayPal with a 2.5% fee and $3.50 minimum, cash in person, check/e-check, and electronic funds transfer for large payments. E-checks are accepted online with no additional service fee, but rejected e-checks can trigger the county’s returned-check fee.
Official source: Contra Costa County ways to pay and tax portal service fee notice.E-check
E-check is accepted online with no additional service fee. Enter routing and account numbers carefully because rejected e-checks can result in a returned-check fee.
Credit/debit card and wallets
Cards and online payment services are convenient, but the percentage fee can be large on high property tax bills. Review the fee before submitting.
Mail, phone and in-person
Use mail, phone, in-person or scheduler options if they fit your deadline. For phone payments, call (925) 608-9500 and keep the confirmation number.
Contra Costa County Tax Payment Tools: Fee Planner, Due Date Checker and Office Router
These tools are for planning help only. They are not an official tax bill, not an official fee quote, not a legal determination, and not county approval. Always verify final amounts and deadlines on the official Contra Costa County tax portal before paying.
Card Fee Planner
Use this to estimate a percentage-based service fee before deciding between card, e-check, mail or in-person payment.
Secured Tax Deadline Checker
Check the standard secured property tax delinquency dates for the tax year planning cycle.
Tax Collector vs Assessor Router
Select your issue to find the better starting office.
Contra Costa County Property Tax Due Dates: December 10 and April 10
For secured property taxes, the first installment is payable by November 1 and delinquent after December 10. The second installment is payable by February 1 and delinquent after April 10.
For the first installment, the county says payment must be made by 5:00 PM in person or electronically by midnight on December 10 before a 10% penalty is imposed. For the second installment, payment must be made by 5:00 PM in person or electronically by midnight on April 10 before a 10% penalty plus a $20 delinquent cost is imposed. If the delinquency date falls on a weekend or holiday, the date extends to the next business day.
Official source: secured property tax due dates and penalties.First installment
Payable November 1 and delinquent after December 10. Both installments may be paid on or before December 10.
Second installment
Payable February 1 and delinquent after April 10. Late second installment can include a 10% penalty plus $20 cost.
After June 30
If unpaid by 5:00 PM on June 30, property becomes tax-defaulted on July 1 with redemption fee and monthly interest added.
Contra Costa County Tax Collector vs Assessor: Which Office Handles Your Problem?
The Treasurer-Tax Collector collects taxes. The Assessor handles assessed value, exemptions, ownership and mailing address changes, and property record questions.
| Your question | Best office | Why |
|---|---|---|
| I need to pay property tax, schedule payment or review tax history. | Tax Collector | The Tax Collector handles tax payment and collection. |
| I did not receive a bill or need a duplicate bill. | Tax Collector / tax portal | Duplicate tax bill amount can be viewed through the portal or requested from Tax Collector. |
| I need to change my mailing address. | Assessor | County secured tax guidance directs change-of-address questions to the Assessor. |
| I need exemption or senior assessment information. | Assessor / State Controller program | Exemptions and postponement programs are not ordinary payment-counter fixes. |
New Contra Costa Property Owners: Why You Still Must Check the Tax Bill
If you recently purchased property in Contra Costa County and do not receive a tax bill, you are still responsible for checking the amount due and paying on time. Failure to receive a bill does not prevent penalties under county guidance.
Annual secured tax bills are mailed once a year in late September through early October and contain stubs for both installments. Partial payments are not accepted for secured property tax installments. If you bought recently, check closing documents, supplemental tax notices, lender escrow instructions and the official tax portal.
Official source: secured property tax information and new property owners.Check APN early
Use your deed, closing paperwork, tax bill, or Assessor record to locate the parcel and confirm the tax account.
Watch for supplemental bills
A purchase or new construction can create supplemental assessment activity. Do not assume your mortgage escrow covers every new bill.
Do not wait for mail
If no bill arrives, use the official portal or call the Tax Collector before delinquency dates.
Contra Costa County Delinquent Property Taxes, Tax Default and Power of Sale
If a secured property tax installment is late, check the official portal for the current balance including any penalty. Do not send a guessed payoff amount.
Contra Costa County secured tax guidance says that if taxes are not paid by 5:00 PM 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. Taxes can remain unpaid for a maximum of five years after default, after which the property becomes subject to power of sale.
Official source: secured property tax delinquency and default rules.Late installment
Check the exact penalty and current balance before paying. Online balances can be affected by pending payments or corrections.
Tax-defaulted status
After June 30 unpaid status, tax-defaulted rules can add redemption fees and monthly interest.
Five-year risk
Long-unpaid taxes can lead to power of sale. Contact the Tax Collector before the situation gets worse.
Pay Contra Costa County Property Taxes by Mail or Phone
If you do not want to pay online, Contra Costa County lists mail and phone payment options. Use the method that fits your proof, timing and fee needs.
Pay by mail
Mail payments to Contra Costa County Treasurer-Tax Collector, P.O. Box 631, Martinez, CA 94553. If paying without a coupon, send to County Tax Collector, P.O. Box 631, Martinez, CA 94553-0063.
Open Pay By MailPay by phone
Call (925) 608-9500. The IVR can announce prior-year taxes, current-year paid and unpaid secured taxes, service fee information, and a confirmation number after payment.
Open Pay By PhoneSenior-friendly phone payment tip
When paying by phone, write down the APN, amount, installment, payment method, confirmation number, date and time. Keep it with your tax bill until the payment appears in the official tax portal.
Official Video: Ways to Pay Contra Costa County Property Taxes
Contra Costa County provides an educational video explaining payment options such as mail, online, in-person and phone payment. Watch the video for general guidance, then verify your specific APN, installment, balance and fee on the official tax portal.
Contra Costa County Tax Collector Map: 625 Court Street, Room 100, Martinez CA
Use this map for directions to the Contra Costa County Treasurer-Tax Collector office in the Finance Building at 625 Court Street, Room 100, Martinez, CA 94553. Confirm holiday closures, parking, and service availability before visiting near deadline dates.
Bring before visiting
- Tax bill or APN
- Payment coupon if available
- Payment method accepted by the office
- Photo ID if needed
- Confirmation number if following up on a payment
Call before final-day visits
- Confirm walk-in hours and holiday closures.
- Ask whether your payment type is accepted.
- Ask whether your issue belongs to the Tax Collector or Assessor.
- Ask how pending payments affect the online balance.
Contra Costa County Property Tax Safety Checklist
This checklist is especially useful for seniors, new owners, out-of-county property owners, family helpers, escrow customers and anyone paying near a delinquency deadline.
Website safety
- Start with contracosta.ca.gov or taxcolp.cccttc.us.
- Avoid ads that look like payment portals.
- Do not enter bank details on non-county pages.
Account safety
- Match APN, address and tax year.
- Select the correct installment.
- Check whether penalties are already included.
Proof safety
- Save confirmation number.
- Verify posting in the portal later.
- Keep bank, card, mail or phone-payment proof.
Official Contra Costa County Tax Links
This guide explains the process in plain language, but final tax amounts, penalties, service fees, office closures, posting status and due-date handling must be verified through official Contra Costa County sources.
More TaxCollectors.org Guides for Property Tax Payment Research
Use these related guides to compare how county tax collector pages explain payment methods, office hours, address formats, tax bill lookup, receipts and assessor-vs-collector routing.
Contra Costa County Tax Collector FAQ
These answers cover the main search intent behind Contra Costa County Tax Collector, pay property taxes online, office hours, office address, APN lookup, secured tax due dates, payment fees, phone payments, and tax-defaulted property questions.
Where is the Contra Costa County Tax Collector office?
The Contra Costa County Treasurer-Tax Collector office is located at Finance Building, 625 Court Street, Room 100, Martinez, CA 94553.
What is the Contra Costa County Tax Collector phone number?
The Tax Collector phone number is (925) 608-9500. TTY users can call 711.
What are Contra Costa County Tax Collector office hours?
Walk-in hours are listed Monday through Friday, 8:00 AM to 5:00 PM, except holidays. Call center and chat hours are listed Monday through Friday, 8:00 AM to 4:00 PM, except holidays.
How do I pay Contra Costa County property taxes online?
Use the official Contra Costa County tax portal. Search your property tax account, verify the APN and installment, review service fees, then save the confirmation number after payment.
When are Contra Costa County secured property taxes due?
The first installment is payable November 1 and delinquent after December 10. The second installment is payable February 1 and delinquent after April 10. If the delinquency date falls on a weekend or holiday, it extends to the next business day.
What are Contra Costa County online payment fees?
Credit cards and online payment services are listed with a 2.5% fee and $3.50 minimum. E-checks are accepted online with no additional service fee, but rejected e-checks can trigger a returned-check fee.
Can I pay Contra Costa County property taxes by phone?
Yes. Call (925) 608-9500. The phone system can provide property tax information, current-year paid and unpaid secured taxes, service fee information, and a payment confirmation number.
Can I pay Contra Costa County property taxes by mail?
Yes. Mail payments to Contra Costa County Treasurer-Tax Collector, P.O. Box 631, Martinez, CA 94553. If submitting without a coupon, send to County Tax Collector, P.O. Box 631, Martinez, CA 94553-0063.
What happens if Contra Costa County property taxes are not paid by June 30?
If secured taxes are not paid by 5:00 PM on June 30, the property becomes tax-defaulted on July 1, with a redemption fee and monthly interest added to unpaid taxes.
Who handles Contra Costa County assessed value or address change questions?
The Contra Costa County Assessor handles assessed value, exemptions, mailing address changes and property record questions. The Tax Collector handles payment and collection.
Is TaxCollectors.org the official Contra Costa County website?
No. TaxCollectors.org is an independent informational guide. Always verify final payment amounts, penalties, office hours, fees, due dates and account status directly with official Contra Costa County sources.
Best Way to Use This Contra Costa County Tax Collector Guide
Start with the official Contra Costa County tax portal if you need to look up or pay secured property taxes. Match the APN, property address, tax year and installment before paying, then save the confirmation number or receipt proof.
Official source: Contra Costa County tax portal.For in-person help, use Finance Building, 625 Court Street, Room 100, Martinez, CA 94553. For mailed payments, use Contra Costa County Treasurer-Tax Collector, P.O. Box 631, Martinez, CA 94553. For payment questions, call (925) 608-9500. For value, exemptions or address changes, use the Assessor.
Official source: Treasurer-Tax Collector and secured property tax information.Independent guide and official-source warning
This TaxCollectors.org page is an independent informational guide for Contra Costa County, California taxpayers. It is not the official Contra Costa County Treasurer-Tax Collector, Contra Costa County Assessor, California State Controller, mortgage servicer, legal adviser or tax adviser.
Before paying, mailing documents, scheduling a payment, using phone payment, visiting the office, relying on a deadline, handling tax-defaulted property, applying for exemptions, or disputing value, verify current details directly with official Contra Costa County and California sources. Payment methods, service fees, office hours, holiday closures, online balances, pending payments, penalties and legal deadlines can change.