California · County guide
San Mateo County property tax appeal
A San Mateo County property tax appeal for 2026, including a decline-in-value appeal, is due November 30, 2026. The county suggests filing by then to protect your rights if the Assessor's own decline-in-value review isn't finished before November 10, 2026. The filing fee is $30 per application.
This season
- Next deadline
- Nov 30, 2026
- Open now
- San Mateo County Assessment Appeals Board
Opens Jul 2, 2026Closes Nov 30, 2026
- Source: Letter To Assessors No. 2026/023: County Assessment Appeals Filing Period for 2026 (BOE, June 2, 2026)Last checked
Check a San Mateo County home for free
Here the check uses your own figures: you enter the assessed value from your notice or tax bill and the year you bought. We compare how much it has grown with the house price index for your area and show the numbers as your figures. You decide and file yourself.
Excellent5.0 out of 5 · Based on reviewsRead reviews →
Reduced my assessment by $112,000!
I couldn’t believe the difference. My property assessment was reduced by $112,000. I’m extremely happy with the outcome!
A $106,300 reduction
We had no idea there was this much room between our original assessment and the final number. Very happy with the outcome.
- Assessor review date
- November 10, 2026
- Filing fee
- $30 per application
- Where to file first
- San Mateo County Assessment Appeals Board
- Office address
- (650) 363-4573
- Our coverage
- Free check available
- Independent guide — not affiliated with San Mateo County or any government agency.
- Last updated
- October 1, 2026
- Sources last checked
- October 1, 2026
- Status
- Verified guide
When and where do I file a San Mateo County property tax appeal?
Who hears a San Mateo County appeal?
One stage. We are not affiliated with this office.
Who hears it: San Mateo County Assessment Appeals Board
Filing: appeal
Open nowWhere is the San Mateo County office?
San Mateo County Assessment Appeals Board[4]
- Phone
- (650) 363-4573
- AAB@
smcgov. org - Online
- Official website
We are not affiliated with this office. Hours can change, so call before you visit.
Which San Mateo County filing windows are coming up?
| Closes | Area | Who hears it | Status |
|---|---|---|---|
| Nov 30, 2026 | Countywide | San Mateo County Assessment Appeals Board · Official source · Last checked Sep 29, 2026 | Open now |
When were past San Mateo County deadlines?
| Tax year | Window | Office |
|---|---|---|
| 2025 | Closed December 1, 2025 | San Mateo County Assessment Appeals Board |
| 2024 | Closed December 2, 2024 | San Mateo County Assessment Appeals Board |
| 2023 | Closed November 30, 2023 | San Mateo County Assessment Appeals Board |
How do I file a San Mateo County appeal?
- Deadline 2026
- November 30, 2026
- Filing fee
- $30 per application
- How to file
- Online portal, which also shows the status of an appeal
What if the San Mateo County Assessor is still reviewing my value?
The county suggests filing an appeal by November 30, 2026 to protect your rights if the Assessor's decline-in-value review isn't finished before November 10, 2026.
When is the deadline to appeal a property tax assessment in San Mateo County?
The soonest deadline we list: San Mateo County, San Mateo County Assessment Appeals Board — Closes November 30, 2026.
- When a filing counts as on timeSan Mateo County Assessment Appeals Board
- San Mateo County's appeal application says a regular-assessment appeal must be postmarked on or before November 30.[1]
- Deadline detailSan Mateo County Assessment Appeals Board · Filing period
- In San Mateo County, the 2026 deadline for a regular appeal (including decline in value) is November 30, 2026.[2]
Who decides a property tax appeal in San Mateo County?
San Mateo County Assessment Appeals Board · Findings for court: San Mateo County notes that written findings of fact are needed to take an adverse AAB decision to Superior Court. San Mateo County Assessment Appeals Board: In San Mateo County the formal appeal is an Assessment Appeal to the Assessment Appeals Board (AAB), separate from the Assessor's informal Decline in Assessed Value Program.
- Appeal stepsSan Mateo County Assessment Appeals Board · Findings for court
- San Mateo County notes that written findings of fact are needed to take an adverse AAB decision to Superior Court.[3]
- What the appeal is calledSan Mateo County Assessment Appeals Board
- In San Mateo County the formal appeal is an Assessment Appeal to the Assessment Appeals Board (AAB), separate from the Assessor's informal Decline in Assessed Value Program.[2]
How do I file a property tax appeal in San Mateo County?
San Mateo County Assessment Appeals Board: San Mateo County's Assessment Appeals Board has an online portal to submit applications and check the status of an appeal. San Mateo County Assessment Appeals Board: San Mateo County's Assessment Appeals portal is where you submit applications online, check your appeal's status, see hearing schedules and download forms.
- How to fileSan Mateo County Assessment Appeals Board
- San Mateo County's Assessment Appeals Board has an online portal to submit applications and check the status of an appeal.[4]
- FormsSan Mateo County Assessment Appeals Board
- San Mateo County's Assessment Appeals portal is where you submit applications online, check your appeal's status, see hearing schedules and download forms.[4]
- Filing feeSan Mateo County Assessment Appeals Board
- San Mateo County charges a $30 filing fee for each application.[3]
- Who may fileSan Mateo County Assessment Appeals Board
- San Mateo County applicants do not need an agent; if they use one, they sign the authorization in Section 2 or attach a separate Agent Authorization.[3]
- Informal reviewSan Mateo County Assessment Appeals Board
- San Mateo County suggests filing an appeal by November 30, 2026 to protect your rights if the Assessor's decline-in-value review isn't finished before November 10, 2026.[2]
- HearingsSan Mateo County Assessment Appeals Board
- In San Mateo County an accepted appeal first goes to a pre-hearing conference (with at least 45 days' notice), where the exchange of information starts and an evidentiary hearing date is set.[2]
What evidence counts in San Mateo County, and can the value go up?
Can the San Mateo County appeals board raise my value?
Yes. Based on the evidence, the San Mateo County Assessment Appeals Board, like every California appeals board, can raise, lower or keep an assessment.
What evidence can I use in San Mateo County?
San Mateo County Assessment Appeals Board: The appeal guide San Mateo County links names three accepted value methods: comparable sales, replacement cost less depreciation, and income; comparable sales are usually the most reliable for homes. San Mateo County Assessment Appeals Board · Exchange: In San Mateo County each accepted appeal is set for a pre-hearing conference, noticed at least 45 days ahead, which starts the exchange of information before the evidentiary hearing.
- Evidence acceptedSan Mateo County Assessment Appeals Board
- The appeal guide San Mateo County links names three accepted value methods: comparable sales, replacement cost less depreciation, and income; comparable sales are usually the most reliable for homes.[5]
- Evidence ruleSan Mateo County Assessment Appeals Board · Exchange
- In San Mateo County each accepted appeal is set for a pre-hearing conference, noticed at least 45 days ahead, which starts the exchange of information before the evidentiary hearing.[2]
- Evidence ruleSan Mateo County Assessment Appeals Board · Sale dates
- Per the guide San Mateo County links, an appeals board may only consider comparable sales no later than 90 days after the valuation date.[5]
Can my assessment go up if I appeal in San Mateo County?
San Mateo County Assessment Appeals Board: The guide San Mateo County links for appellants says an appeals board, based on the evidence, can increase, decrease or not change an assessment.
- Can the value go up?San Mateo County Assessment Appeals Board
- The guide San Mateo County links for appellants says an appeals board, based on the evidence, can increase, decrease or not change an assessment.[5]
Which exemptions can lower my bill without an appeal?
San Mateo County owners who live in their home on January 1 can claim a $7,000 Homeowners' Exemption for free; new owners are mailed an application.
- Homeowner exemption
- San Mateo County owners who live in their home on January 1 can claim a $7,000 Homeowners' Exemption for free; new owners are mailed an application.[6]
What do San Mateo County property taxes and assessments look like?
Figures from public records and the Census, each with its source. They describe the county's homes as a group, not the value of any one home.
How much could a lower assessment save on San Mateo County property taxes?
Tax rate used: 1.123% of assessed value (county average, fiscal 2024-25).
| Example | Tax saved |
|---|---|
| $10,000 less assessed value | $112 a year |
| 10% less on a home assessed at $1,559,600 (the Census median home value) | $1,751 a year |
These are examples: the tax rate times a lower assessed value. Exemptions, credits, caps and phase-ins can make the real change smaller. This is not a prediction for any home. Rate source: BOE Annual Report 2024-25, Table 14: average tax rate by county (Property Tax Allocations, BOE Open Data Portal).
What do homeowners in San Mateo County pay in property tax?
The median owner-occupied home in San Mateo County was worth $1,559,600, and the median property tax its owners paid was $9,519 a year, according to the Census Bureau's American Community Survey.
- Median home value
- $1,559,600
- Margin of error ±$16,159.
- Median property tax paid per year
- $9,519
- Margin of error ±$153.
- Median tax as a share of median value
- 0.61%
- A ratio of two medians, not a tax rate. Your own bill depends on your assessment and local levies.
- Owner-occupied homes
- 154,607
- Margin of error ±1,889.
These are survey estimates of what owners reported about their own homes. They are not assessed values, not tax rates, and not an opinion of what any home is worth.
They cannot tell you whether your own assessment is fair. That takes a comparison with similar homes, which we offer only in counties we have researched.
Median home value: San Mateo County compared
- San Mateo County$1,559,600
- Typical California county$481,100
- Typical US county$185,300
San Mateo County $1,559,600; Typical California county $481,100; Typical US county $185,300
Median property tax paid: San Mateo County compared
- San Mateo County$9,519
- Typical California county$3,294
- Typical US county$1,619
San Mateo County $9,519 a year; Typical California county $3,294 a year; Typical US county $1,619 a year
San Mateo County filing windows on a calendar
- Open
- Opens soon
- Forecast
- San Mateo County Assessment Appeals BoardNov 30, 2026 · Open now
The dashed line marks today.
San Mateo County Assessment Appeals Board: Nov 30, 2026
How often is property reassessed in San Mateo County?
San Mateo County sets a base year value when a property changes ownership or is built on, then raises it by no more than 2% a year; Prop 8 values are reviewed every January 1. The San Mateo County Assessor compares assessed value with market value as of January 1.
- Reassessment cycle
- San Mateo County sets a base year value when a property changes ownership or is built on, then raises it by no more than 2% a year; Prop 8 values are reviewed every January 1.[7]
- Valuation date
- The San Mateo County Assessor compares assessed value with market value as of January 1.[8]
- Level of assessmentDecline in value
- When a San Mateo County property's January 1 market value is lower than its factored base year value, Prop 8 allows a temporary reduction.[8]
Homes in San Mateo County
From the Census Bureau's American Community Survey: how old the homes are, what kind they are, what owners say they are worth and the property taxes they pay. These figures describe all homes together, not any one home.
- Median year built
- 1966
- All housing units, owned and rented
- Single-family houses, detached or attached
- 64%
- of 287,184 housing units
- Owned homes with a mortgage or similar loan
- 66%
- of 154,607 owner-occupied homes
Home values reported by owners
- Less than $50,0001%
- $50,000 to $99,999<1%
- $100,000 to $199,9991%
- $200,000 to $299,9991%
- $300,000 to $399,9991%
- $400,000 to $499,9991%
- $500,000 to $749,9994%
- $750,000 to $999,99910%
- $1,000,000 to $1,999,99946%
- $2,000,000 or more35%
Home values reported by owners in San Mateo County: Less than $50,000 1%; $50,000 to $99,999 <1%; $100,000 to $199,999 1%; $200,000 to $299,999 1%; $300,000 to $399,999 1%; $400,000 to $499,999 1%; $500,000 to $749,999 4%; $750,000 to $999,999 10%; $1,000,000 to $1,999,999 46%; $2,000,000 or more 35%.
Property taxes owners pay a year
- No real estate taxes2%
- Less than $8002%
- $800 to $1,4992%
- $1,500 to $1,9993%
- $2,000 to $2,9995%
- $3,000 or more86%
Property taxes owners pay a year in San Mateo County: No real estate taxes 2%; Less than $800 2%; $800 to $1,499 2%; $1,500 to $1,999 3%; $2,000 to $2,999 5%; $3,000 or more 86%.
Source: U.S. Census Bureau, American Community Survey (2020–2024 5-year estimates, tables B25075, B25102, B25035, B25024 and B25081), retrieved Oct 1, 2026. Survey estimates have a margin of error.
More questions about San Mateo County property tax appeals
When is the San Mateo County property tax appeal deadline?
The San Mateo County Assessment Appeals Board window closes November 30, 2026.[9][10]
Is there a fee to file a property tax appeal in San Mateo County?
San Mateo County charges a $30 filing fee for each application.[3]
Where do I file an assessment appeal in San Mateo County?
San Mateo County's Assessment Appeals Board has an online portal to submit applications and check the status of an appeal.[4]
Can my assessed value go up if I appeal in San Mateo County?
The guide San Mateo County links for appellants says an appeals board, based on the evidence, can increase, decrease or not change an assessment.[5]
What other rules apply in San Mateo County?
San Mateo County Assessment Appeals Board: San Mateo County appellants must still pay property taxes on time; if a reduction is granted they receive a refund with interest.
- Paying the tax while you appealSan Mateo County Assessment Appeals Board
- San Mateo County appellants must still pay property taxes on time; if a reduction is granted they receive a refund with interest.[3]
Property tax guides for San Mateo County homeowners
- How Comparable Homes Are Chosen, and Why It MattersCalifornia · San Mateo County
- How to Appeal Your Property Taxes YourselfCalifornia · San Mateo County
- Assessed Value vs. Market Value: How They Differ by StateCalifornia · San Mateo County
- Homestead and Other Exemptions to Check FirstCalifornia · San Mateo County
- Homestead Exemption: What It Is and How to Get ItCalifornia · San Mateo County
- How to Lower Your Property Taxes: What to Check FirstCalifornia · San Mateo County
Counties next to San Mateo County
- Santa Cruz County property tax appealsFree check availableNext deadline: Nov 30, 2026
- Santa Clara County property tax appealsWaitlist open
- Alameda County property tax appealsWaitlist open
- San Francisco County property tax appealsWaitlist open
Check a San Mateo County home free
You decide and file yourself.
Where do these facts come from?
- [1]San Mateo County Assessment Appeal Application (BOE-305-AH with county header, 2023 filing year, PDF)Official guide or FAQ · last checked Oct 1, 2026
- [2]About Assessment Appeals | County of San Mateo, CAOfficial guide or FAQ · last checked Sep 30, 2026
- [3]Preparing your appeals application - County of San Mateo (Wayback capture 2026-05-16)Official guide or FAQ · last checked Sep 30, 2026
- [4]Assessment Appeals Board - County of San MateoOfficial guide or FAQ · last checked Sep 29, 2026
- [5]Publication 30 - Residential Property Assessment Appeals (State Board of Equalization, hosted by County of San Mateo, PDF)Official notice, form, calendar or rules · last checked Sep 30, 2026
- [6]Homeowners’ Exemption | San Mateo County Assessor-County Clerk-Recorder & Elections - ACREOfficial guide or FAQ · last checked Sep 30, 2026
- [7]How We Assess the Value of Your Property | San Mateo County Assessor-County Clerk-Recorder & Elections - ACREOfficial guide or FAQ · last checked Sep 30, 2026
- [8]Property Tax Relief: Market Value Decline | San Mateo County Assessor-County Clerk-RecorderOfficial guide or FAQ · last checked Sep 29, 2026
- [9]Letter To Assessors No. 2026/023: County Assessment Appeals Filing Period for 2026 (BOE, June 2, 2026)Official notice, form, calendar or rules · last checked Sep 25, 2026
- [10]Publication 30: Residential Property Assessment Appeals (California State Board of Equalization, February 2020)Official guide or FAQ · last checked Sep 25, 2026
- [11]Letter To Assessors No. 2025/020: County Assessment Appeals Filing Period for 2025 (BOE, July 7, 2025)Official notice, form, calendar or rules · last checked Oct 1, 2026
- [12]Letter To Assessors No. 2024/022: County Assessment Appeals Filing Period for 2024 (BOE, June 25, 2024)Official notice, form, calendar or rules · last checked Oct 1, 2026
- [13]Letter To Assessors No. 2023/023: County Assessment Appeals Filing Period for 2023 (BOE, June 22, 2023)Official notice, form, calendar or rules · last checked Oct 1, 2026
- 14.U.S. Census Bureau, ACS 2020–2024 5-year estimates, table B25077: Median value (dollars), owner-occupied housing units — San Mateo County, California
- 15.U.S. Census Bureau, ACS 2020–2024 5-year estimates, table B25103: Median real estate taxes paid, owner-occupied housing units — San Mateo County, California
- 16.U.S. Census Bureau, ACS 2020–2024 5-year estimates, table B25003: Tenure (owner- and renter-occupied housing units) — San Mateo County, California
Data credits: Census ACS (public domain) · Census county adjacency (public domain)
Not affiliated with San Mateo County or any government agency. Not legal advice. Not an appraisal.