The Sonoma County Assessor's Office is open Monday through Friday, 8 am to 5 pm. Please note our holiday schedule below.
Si necesita assistencia en Español favor de llamar a la oficina 707-565-6075 entre las 8:00 am y 5:00 pm de Lunes a Jueves.
| Jan 1 | The Lien Date, when property taxes become a lien on the property. This is also the date when filing begins for various exemptions. |
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| Feb 15 | This is the last date you can file a timely claim for the Welfare, Museum, Cemetery, Homeowner, Veteran, Disabled Veteran, Historical Aircraft, and various miscellaneous exemptions. This is also the last date you can file a timely claim for a Church or Religious Exemption, and this is the last date you can file a timely Affdavit for 4 Percent Assessment of Commercial Vessels. |
| Apr 1 | This is the due date for filing Business Property Statements, Agricultural Property Statements, Apartment House Property Statements, and Mining and Quarrying Production Reports. It is set by the Assessor, and may vary from year to year. When mailed, these statements and reports must be postmarked by May 7 or they will be assessed a penalty. |
| Apr 10 | The deadline for payment of the second installment of regular secured property taxes without penalty (other payment periods may apply for supplemental assessments and escaped assessments). |
| May 7 | The final deadline for filing Property Statements. They must be either in our office or postmarked by the U.S. Post Office by this date. |
| May 16 to Aug 31 | The period for filing claims for Senior Citizens Tax Assistance. |
| Jul 1 | The date each year on which the Assessment Roll is delivered by the Assessor to the County Auditor. |
| Jul 2 to Nov 30 | The period during which the Clerk of the Board of Supervisors accepts applications for changes in assessments (appeals) for the regular Secured Assessment Roll (other filing periods may apply for supplemental assessments and escaped assessments). |
| Aug 31 | The deadline for payment of unsecured property taxes without penalty. |
| Dec 10 | The deadline for payment of the first installment of regular secured property taxes without penalty (other payment periods may apply for supplemental assessments and escaped assessments). This is also the "late filing" deadline for Homeowner Exemptions--the last day you can file and still qualify for a partial exemption. Disabled Veteran Exemption applicants can file after this date and still qualify for a partial exemption. |
| Mon, Jan 1 | New Year's Day |
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| Mon, Jan 15 | Martin Luther King Jr Day |
| Mon, Feb 12 | Lincoln's Birthday |
| Mon, Feb 19 | Presidents' Day |
| Mon, May 28 | Memorial Day |
| Wed, Jul 4 | Independence Day |
| Mon, Sep 3 | Labor Day |
| Mon, Nov 12 | Veteran's Day |
| Thu, Nov 22 | Thanksgiving Day |
| Fri, Nov 23 | Day after Thanksgiving |
| Tue, Dec 25 | Christmas Day |