Contra Costa County, California elections office: address and phone for 2026
The California Secretary of State lists the Contra Costa County Elections Office at 555 Escobar Street, Martinez, CA 94553, phone 925-335-7800. For early voting, see every Contra Costa County early voting location with days and hours.
Contra Costa County elections office
Contra Costa County Elections Office
Office: 555 Escobar Street, Martinez, CA 94553
Mailing address: P.O. Box 271, Martinez, CA 94553
Phone: 925-335-7800
Regular office hours: 8 a.m. to 5 p.m.
California voting dates for Contra Costa County voters
| Date | What |
|---|---|
| Mon, Oct 5 | Ballots go out to all voters Every active registered voter is mailed a ballot. Drop boxes open in early October. source |
| Mon, Oct 5, 8:00 AM | Early voting opens Early voting sites open Oct 5; vote centers in Voter's Choice Act counties open Oct 24. Hours and locations vary by county. source |
| Mon, Oct 19 | Last day to register Last day to register for the Nov 3 general election. After that, use same-day (conditional) registration at your county elections office or a voting location. source |
| Tue, Oct 27 | Last day to request a replacement ballot by mail After this, ask in person at your county elections office. source |
| Tue, Nov 3, 8:00 PM | Election Day: polls open 7:00 a.m. to 8:00 p.m. Find your polling place or vote center through your county elections office. source |
| Tue, Nov 3, 8:00 PM | Register and vote the same day Conditional voter registration runs Oct 20–Nov 3; you'll vote a provisional ballot that counts once your registration is verified. Polls close at 8 p.m. source |
| Tue, Nov 3, 8:00 PM | Return your ballot Every active voter is mailed a ballot. Drop it off by 8 p.m., or mail it postmarked by Election Day so it arrives by Nov 10. source |
Contra Costa County voting questions
What is the phone number for the Contra Costa County elections office?
925-335-7800, the Elections Office (Contra Costa County's elections office on the California Secretary of State, County Elections Offices list).
What is the address of the Contra Costa County elections office?
555 Escobar Street, Martinez, CA 94553. Mailing address: P.O. Box 271, Martinez, CA 94553.
When does early voting start in Contra Costa County?
Early voting opens Monday, October 5, 2026. Early voting sites open Oct 5; vote centers in Voter's Choice Act counties open Oct 24. Hours and locations vary by county. Contra Costa County's locations are on our Contra Costa County early voting page.
More for California voters
- Who is on the California ballot: every candidate on the state's official list, race by race.
- California voting deadlines 2026: registration, mail ballots, early voting and Election Day.
- California early voting locations we have read so far, with days and hours.
- Every California county's office.
- Early voting dates in every state.
Other California counties: Alameda, Alpine, Amador, Butte, Calaveras, Colusa, Del Norte, El Dorado, Fresno, Glenn, Humboldt, Imperial, Inyo, Kern, Kings, Lake, Lassen, Los Angeles, Madera, Marin, Mariposa, Mendocino, Merced, Modoc, Mono, Monterey, Napa, Nevada, Orange, Placer, Plumas, Riverside, Sacramento, San Benito, San Bernardino, San Diego, San Francisco, San Joaquin, San Luis Obispo, San Mateo, Santa Barbara, Santa Clara, Santa Cruz, Shasta, Sierra, Siskiyou, Solano, Sonoma, Stanislaus, Sutter, Tehama, Trinity, Tulare, Tuolumne, Ventura, Yolo, Yuba.
Office details are from the California Secretary of State, County Elections Offices (checked October 14, 2026). Dates are California's, each linked to its source. Call the office before you go.