San Mateo County Property Tax Appeal

Use this guide to find the filing window, appeal office, submission caveats, informal review option, and hearing preparation notes for San Mateo County property tax appeals.

Key Dates

• File a regular 2026 San Mateo County assessment appeal between July 2, 2026, and November 30, 2026.¹

Where To File

• San Mateo County property owners may appeal assessor decisions to the Assessment Appeals Board, and formal appeals must be filed with the Clerk of the Board of Supervisors at the County Government Center.²³

Forms And Fees

• Use the Clerk of the Board filing path identified by San Mateo County. We have not yet found a specific San Mateo County form name, filing fee, or a date when those details are expected to be published, so we will keep searching and update this guide when we find the current form or fee.³⁴⁵

Submission Methods

• San Mateo County points taxpayers to the Clerk of the Board at the County Government Center. We have not yet found an official online filing path or a date when one is expected to be available, so we will keep searching and update this guide when San Mateo County publishes accepted submission methods.⁶⁵

Informal Review

• If you disagree with an assessment, contact the San Mateo County Assessor division within 15 days after receiving the assessment notice.⁷

Evidence And Hearing Process

• Prepare evidence that supports the value you are requesting. BOE gives this statewide hearing-preparation guidance; we have not yet found separate San Mateo County hearing rules or a date when additional rules are expected to be published, so we will keep searching and update this guide if we find them.⁸

What Still Needs Verification

• We have not yet found San Mateo County's current appeal form name, filing fee, or full list of accepted submission methods. Check with the Clerk of the Board before submitting; we will keep searching and update this guide when those details are found.⁵

Footnotes

1. BOE lists San Mateo County's 2026 regular assessment appeal deadline as November 30. Source: California BOE LTA 2026/023 Regular Assessment Filing Periods. ↩

2. San Mateo County ACRE says property owners may appeal assessor decisions to the Assessment Appeals Board. Source: San Mateo County ACRE Appeal An Assessment Page. ↩

3. San Mateo County ACRE states that appeals must be filed with the Clerk of the Board of Supervisors at the County Government Center. Source: San Mateo County ACRE Appeal An Assessment Page. ↩ ↩²

4. BOE says some counties may charge a filing or processing fee and instructs taxpayers to check with the county clerk of the board to find out whether fees apply. Sources: San Mateo County ACRE Appeal An Assessment Page, California BOE Assessment Appeals FAQ. ↩

5. San Mateo County ACRE directs appeals to the Clerk of the Board, and BOE says to check with the county clerk of the board for fee and local filing details. Sources: San Mateo County ACRE Appeal An Assessment Page, California BOE Assessment Appeals FAQ. ↩ ↩² ↩³

6. San Mateo County ACRE identifies filing with the Clerk of the Board at the County Government Center. Source: San Mateo County ACRE Appeal An Assessment Page. ↩

7. San Mateo County ACRE says a property owner who disagrees with an assessment should contact the Assessor division within 15 days of receiving the assessment notice. Source: San Mateo County ACRE Appeal An Assessment Page. ↩

8. BOE says taxpayers should be prepared to present evidence supporting the requested value. Source: California BOE Assessment Appeals FAQ. ↩