Contra Costa County property tax calculator

How Contra Costa County property tax is calculated

Every parcel pays the countywide 1% Prop 13 tax on its assessed value plus the bond rates of the districts in its tax rate area (TRA); the assessed value is the purchase price grown by at most 2% a year.^[1][3][4]

Tax = (Assessed value − $7,000) × TRA rate + special assessments

A Concord home assessed at $650,000 pays $7,067.86 at 1.0992%. In Richmond a $500,000 home pays $6,996.66; the same value in Concord would pay $5,419.06, so the Richmond address costs $1,578 more a year.^[1]

Contra Costa property tax rates by city

The 2024-25 Detail of Tax Rates lists 1,100 tax rate areas, from 1.0505% in parts of Antioch to 1.4192% in Richmond.^[1] Four common ones:

FY 2024-25 rates (Auditor-Controller, October 2024). The 2025-26 book exists but could not be read from the county website; the 1% levy is fixed by Prop 13 and only the bond rates change.

The cities share three bond rates: BART (0.0148%), Contra Costa Community College (0.0142%) and the East Bay Regional Park District (0.0013%), 3.0300% together.^[1] The school district decides most of the gap. Richmond adds two things no other city in the table has: a 0.14% City of Richmond pension tax and 0.2489% in West Contra Costa Unified bonds.^[1]

Contra Costa property tax due dates

Secured bills are mailed by November 1. The first installment is delinquent after December 10 with a 10% penalty, and the second after April 10 with 10% plus a $20 cost; both can be paid by December 10.^[9][6]

• July 2 — Appeal filing period opens
• Late September – early October (always by November 1) — Secured bills mailed
• Due November 1; delinquent after December 10 (5:00 p.m. in person, midnight online) — 1st installment (10%)
• November 30, 2026 — Appeal and informal review deadline
• Due February 1; delinquent after April 10 (5:00 p.m. in person, midnight online) — 2nd installment (10% plus $20 delinquent cost)
• February 15 — Exemption claims (homeowners', veterans')
• Unpaid by 5:00 p.m. June 30; defaulted July 1 — Tax-defaulted ($15 redemption fee plus 1.5% a month; property subject to power of sale after five years)
• Mailed July 1; delinquent after August 31 — Unsecured bills (10% plus $30 collection fee; 1.5% a month from November 1)

The Treasurer-Tax Collector does not accept partial payments of a current secured bill; only delinquent taxes can go on a payment plan.^[9][14] Dates for other counties are on property tax due dates.

Exemptions and senior parcel tax relief

The homeowners' exemption takes $7,000 off the assessed value of a principal residence, worth about $77 a year in Concord; claim it with the Assessor by February 15.^[5][6]

There is no county senior exemption from the 1% levy or from bond rates, but many school and district parcel taxes on Contra Costa bills exempt seniors, and they are marked with an asterisk on the bill.^[15]

Seniors, blind or disabled owners can defer taxes with the State Controller's Property Tax Postponement program, and owners 55 and older can carry their Prop 13 base to a new home under Prop 19.^[15][16] Other counties' programs are on property tax exemptions for seniors.

How to appeal your Contra Costa assessment

For the 2026-27 roll you have until November 30, 2026, both for the Assessor's free informal review and for a formal appeal to the Assessment Appeals Board.^[10][8][11]

1. Free informal review (Prop 8): return the Request for Value Review (form VAL 4695) with your opinion of value as of January 1, 2026 and up to three comparable sales dated before March 31, 2026.^[10]
2. Formal appeal: mail the Assessment Appeal Application with a $40 check to the Assessment Appeals Board, 1025 Escobar Street, 1st Floor, Martinez, CA 94553, between July 2 and November 30.^[8]
3. Supplemental or escape assessment: appeal within 60 days of the Assessor's notice.^[8]
4. Keep paying: bills already received must be paid; if the value is lowered, the tax is adjusted.^[10]

The deadline is much later than San Francisco's September 15; see the San Francisco property tax page for the city's single rate. Other counties' windows are in the property tax assessment appeal guide (an estimate, not an appraisal, and not legal advice).

What Contra Costa homeowners typically pay

Census figures for 2024 put the median property tax paid by Contra Costa County homeowners at $7,378 on a median home value of $873,100, an effective rate of about 0.85%.^[12][13]

California's rules, including the Prop 13 base, are on the California property tax calculator.

Common mistakes

• Using a city-wide rate. Richmond alone has 59 tax rate areas at 1.4192%, and other cities split between school districts; your TRA is on the bill.^[1]
• Sending part of the bill. A partial payment of the current secured bill is not accepted, so a short payment can make the whole installment late.^[9]
• Missing the senior parcel tax forms. They are separate from the homeowners' exemption and filed with each district. Compare counties from the property tax calculator.