AppealDesk

San Mateo County Property Tax Appeal, California

Travis BunnTravis Bunn·Updated July 24, 2026

San Mateo County is located on the San Francisco Peninsula in California, with Redwood City serving as the county seat. Major cities include San Mateo, Daly City, Burlingame, South San Francisco, and Menlo Park. With a median home value of approximately $1,441,300 and an effective property tax rate of 1.26%, San Mateo County homeowners face some of the highest property tax burdens in the nation. The county's median annual property tax bill of approximately $8,637 to $9,758 is substantially higher than the national median of $2,400, making property tax appeals particularly important for local homeowners seeking to reduce their tax liability.

Notable cities: Redwood City, San Mateo, Daly City, Burlingame, South San Francisco, Menlo Park

Median Home

$1,441,300

Tax Rate

1.26%

Annual Tax

$8,637

Population

746,509

On the typical San Mateo County home, valued near $1,441,300 at the county’s effective tax rate of 1.26%, an over-assessment of even 10% means you are overpaying year after year until you appeal it. Here is how to find out if yours qualifies.

2026 Appeal Deadline: November 30, 2026

That is at most 97 days away. Your exact date is on your assessment notice, so do not wait on it.

For regular assessment appeals (decline in value, base year value, personal property), applications must be filed between July 2, 2026 and November 30, 2026. For supplemental assessments, escape assessments, or roll corrections, appeals must be filed within 60 days of the mailing date on the assessment notice or postmark date, whichever is later. There are no deadline extensions or exceptions regardless of circumstances.

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California residential street with palm trees at sunset. San Mateo County appeal guide.

How San Mateo County Assesses Property

100%of market value

Assessed by: San Mateo County Assessor-County Clerk-Recorder & Elections (ACRE)

Assessment cycle: annual

Notices typically mailed: June through August

In San Mateo County, properties are assessed annually at 100% of their market value as of January 1st (the lien date), subject to Proposition 13 limitations. California law establishes a 100% assessment ratio, meaning the assessed value equals the full market value for newly purchased properties. For example, if your home's market value is $1,441,300 at California's 100% assessment ratio, your assessed value would be $1,441,300, resulting in approximately $18,160 in annual taxes at the county's effective rate of 1.26%. However, Proposition 13 limits annual increases to 2% for properties that have not changed ownership, so long-term owners may have assessed values well below current market value.

The Appeal Process

Appeals are heard by the Assessment Appeals Board. The Assessment Appeals Board consists of three impartial commissioners who act in a quasi-judicial capacity, independent from both the Assessor's and Tax Collector's Offices. All hearings are conducted fully in-person at the Board of Supervisors' Chambers, 500 County Center, 1st Floor, Redwood City. The board hears evidence from both parties before rendering their decision on property value.

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Step 1: Consider filing an informal Decline in Value application with the Assessor's Office by October 31, 2026. This allows for an informal review and potential mutual agreement before pursuing a formal appeal.

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Step 2: Obtain and complete the Application for Changed Assessment (Form BOE-305-AH). Download from the county website or request from the Assessment Appeals Board Clerk at (650) 363-4573 or AAB@smcgov.org. Complete all sections accurately and provide your opinion of value.

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Step 3: Gather supporting documentation including comparable property sales data, recent appraisals, photos showing property condition, repair estimates for defects, and any evidence supporting your claim that the assessed value exceeds fair market value as of January 1.

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Step 4: File your appeal with the required $30 non-refundable filing fee. Submit the original application plus two copies between July 2 and November 30, 2026 (for regular assessments). Make check payable to 'San Mateo County AAB.' File by mail (postmarked by deadline) or in-person.

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Step 5: Attend the pre-hearing conference. Within 2-3 months, you'll be notified at least 45 days before your pre-hearing conference. This allows exchange of information between parties and may result in a stipulation (settlement) with the Assessor's Office.

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Step 6: Present evidence at the evidentiary hearing before the Assessment Appeals Board. Bring eight copies of all documents. The three-member board will hear testimony from both you and the Assessor's Office in person at the Board of Supervisors' Chambers. The board can lower, raise, or confirm the assessed value.

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Step 7: Receive the board's decision by mail. The decision is final and may not be reheard by the board unless ordered by the court. If you are granted a reduction, you will receive a refund with interest. You must continue paying property taxes during the appeal process.

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Step 8: If you disagree with the Assessment Appeals Board's decision, you may appeal to California Superior Court within the time frame specified in the decision.

Required form: Application for Changed Assessment (Form BOE-305-AH)

Filing Methods

mail:Mail original application plus two copies with $30 filing fee (check payable to 'San Mateo County AAB') to: Assessment Appeals Board, 500 County Center, 5th Floor BOS104, Redwood City, CA 94063. Must be postmarked by deadline.
in-person:Deliver original application plus two copies with $30 filing fee to: Assessment Appeals Board, 500 County Center, 5th Floor BOS104, Redwood City, CA 94063. Office hours: 8:00 AM - 5:00 PM Monday through Friday.
email:Contact AAB@smcgov.org or call (650) 363-4573 for information about electronic filing options.

Evidence to Bring

Comparable property sales data from the neighborhoodRecent professional appraisalPhotos documenting property condition or defectsRepair estimates for structural issues or needed repairsEvidence of market value declineDocumentation of property characteristics affecting value

San Mateo County Assessor Contact

San Mateo County Assessor-County Clerk-Recorder & Elections (ACRE)

Phone: (650) 363-4500

Address: 555 County Center, 1st Floor, Redwood City, CA 94063

Website: https://smcacre.gov/assessor

Hours: 8:00 AM - 5:00 PM Monday through Friday

Tax Exemptions in San Mateo County

Homeowner's Exemption

$7,000 reduction in assessed value

Reduces the assessed value of an owner-occupied primary residence for property tax purposes.

Eligibility: Must own and occupy the property as principal place of residence as of January 1. Only one exemption per homeowner statewide.Deadline: February 15 for full exemption; late filing by December 10 allows 80% exemption ($5,600). Once granted, exemption renews automatically.

Disabled Veterans' Exemption - Basic

Up to $175,298 (basic exemption, adjusted annually for inflation)

Property tax exemption for qualifying disabled veterans or their unmarried surviving spouses on their principal place of residence.

Eligibility: Veterans rated 100% disabled or compensated at 100% rate due to unemployability from service-connected injury or disease. Must be California resident as of January 1.Deadline: February 15 annually. Contact Assessor's Office at (650) 363-4500 for application form BOE-261-G.

Disabled Veterans' Exemption - Low Income

Up to $271,009 (low-income exemption, adjusted annually for inflation)

Enhanced property tax exemption for qualifying low-income disabled veterans.

Eligibility: Veterans with 100% disability or unemployability whose total household income does not exceed $78,718 (adjusted annually). Cannot receive both Veteran's and Homeowner's Exemption on same property.Deadline: February 15 annually. Contact Assessor's Office at (650) 363-4500.

Property Tax Postponement Program

Varies - postpones full property tax payment

State program allowing eligible homeowners to postpone payment of current-year property taxes on primary residence.

Eligibility: Seniors age 62+, blind, or disabled persons who meet income and equity requirements. Property must be principal residence.Deadline: Applications accepted October 1 to February 10 each year. Apply through State Controller's Office at (800) 952-5661 or postponement@sco.ca.gov.

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Frequently Asked Questions

What is the deadline to appeal my property taxes in San Mateo County for 2026?
The deadline to file a property tax appeal in San Mateo County for regular assessments (decline in value, base year value, or personal property) is November 30, 2026. The filing window opens July 2, 2026. For supplemental assessments, escape assessments, or roll corrections, you must file within 60 days of the mailing date printed on your assessment notice or the postmark date, whichever is later. There are no deadline extensions or exceptions regardless of your circumstances, so it's critical to file on time to preserve your appeal rights.
How much does it cost to file a property tax appeal in San Mateo County?
Filing a property tax appeal with the San Mateo County Assessment Appeals Board requires a non-refundable $30 filing fee per parcel. The check should be made payable to 'San Mateo County AAB' and submitted along with the original Application for Changed Assessment (Form BOE-305-AH) plus two copies. This fee covers the administrative costs of processing your appeal and scheduling your hearing before the three-member Assessment Appeals Board. If you're granted a reduction in your assessed value, you'll receive a property tax refund with interest that typically far exceeds the filing fee.
What evidence do I need to win my property tax appeal in San Mateo County?
To succeed with your San Mateo County property tax appeal, you should bring eight copies of all supporting documents to your hearing. The most persuasive evidence includes comparable sales data from your neighborhood showing similar properties sold for less than your assessed value, a recent professional appraisal, photographs documenting property condition or defects, and repair estimates for any structural issues. Your evidence must support that your property's fair market value as of January 1 of the tax year is less than the Assessor's valuation. The Assessment Appeals Board bases its decision on the evidence presented, so thorough documentation is essential.
Should I try the informal Decline in Value program before filing a formal appeal in San Mateo County?
Yes, San Mateo County offers an informal Decline in Value program that many homeowners should consider before filing a formal Assessment Appeals Board appeal. You can apply to this program by October 31, 2026, to have an informal review of your property's assessment and potentially reach a mutual agreement with the Assessor's Office regarding your property value. This process is less formal and can be faster than a formal appeal. However, if you don't receive results by November 10, 2026, or disagree with the outcome, you should file a formal appeal by November 30, 2026 to protect your appeal rights. You can withdraw your formal appeal if the informal process succeeds.
How much can I save by appealing my property taxes in San Mateo County?
Given San Mateo County's effective tax rate of approximately 1.26% and median home value of $1,441,300, even a modest reduction in assessed value can yield significant savings. For example, if you successfully reduce your assessed value by $100,000, you would save approximately $1,260 annually in property taxes. On the typical San Mateo County home, a 10% assessment reduction could save homeowners $1,800 or more per year. These savings continue year after year until your next reassessment, and successful appellants receive a refund with interest for any overpayment. With the county's exceptionally high property values, the potential savings make appeals particularly worthwhile.
What happens at my San Mateo County Assessment Appeals Board hearing?
Your San Mateo County Assessment Appeals Board hearing is conducted in-person at the Board of Supervisors' Chambers, 500 County Center, 1st Floor, Redwood City. The hearing is quasi-judicial and public, presided over by three impartial commissioners who are independent from the Assessor's Office. Both you and the Assessor will present testimony and evidence supporting your positions on the property's fair market value. You should bring eight copies of all documents. Before the formal hearing, you'll attend a pre-hearing conference to exchange information with the Assessor, which sometimes results in a settlement. After hearing all evidence, the board can lower, raise, or confirm your assessed value, and their written decision is mailed to you.
Can I file a San Mateo County property tax appeal online?
Currently, San Mateo County does not offer a fully online portal for filing property tax appeals, though the county has been working to develop an electronic system. To file your appeal, you must submit the original Application for Changed Assessment (Form BOE-305-AH) plus two copies with your $30 filing fee either by mail (postmarked by November 30, 2026) or in-person at the Assessment Appeals Board office at 500 County Center, 5th Floor BOS104, Redwood City. You can download the form from the county website at smcgov.org or request it by calling (650) 363-4573 or emailing AAB@smcgov.org. Contact the Assessment Appeals Board for the most current filing options.
Do I have to pay my property taxes while my San Mateo County appeal is pending?
Yes, you must continue paying your property taxes on time even while your San Mateo County appeal is pending with the Assessment Appeals Board. Filing an appeal does not waive your obligation to pay your tax bill by the due dates (December 10 for first installment, April 10 for second installment). If you don't pay on time, you'll face penalties and interest regardless of your appeal status. However, if your appeal is successful and the board lowers your assessed value, you will receive a refund with interest for any overpayment after the board issues its decision. The refund typically arrives 30-60 days after a successful hearing.

Official Resources

San Mateo County Assessor Official Website →

Official site for property assessment information, exemption applications, parcel searches, and assessment roll summaries.

San Mateo County Assessment Appeals Board →

Information about filing appeals, hearing schedules, deadlines, and the formal appeals process.

San Mateo County Property Tax Relief Programs →

Details about the Decline in Value program, Assessment Appeals Board filing deadlines, and property tax relief options.

California State Board of Equalization Property Tax Information →

Statewide property tax resources, exemption forms, Publication 30 for residential appeals, and taxpayer rights information.

For state-wide appeal information including California's assessment ratio and deadlines, see our California Property Tax Appeal Guide →

Considering professional help with your appeal? Compare pricing, coverage, and pros/cons in our Best Property Tax Appeal Services (2026) or browse side-by-side service comparisons →

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← All California property tax appeal info

Sources: https://smcacre.gov/assessor/property-tax-relief | https://www.smcgov.org/ceo/assessment-appeals-board | https://www.jvmlending.com/blog/san-mateo-county-property-tax-101-tips-for-homeowners/ | https://www.smcgov.org/ceo/about-assessment-appeals | https://smcacre.gov/assessor | https://www.appealdesk.com/appeals/california/san-mateo

Last verified: 2026-07-24