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California · County guide

Sonoma County, California property tax appeals

A Sonoma County property tax appeal starts with the Sonoma County Assessment Appeals Board. The next deadline is Nov 30, 2026 for the Sonoma County Assessment Appeals Board. The filing fee is $30.

This season

Next deadline
Nov 30, 2026
Open now
Sonoma 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 Sonoma County home for free

Enter the address or parcel number from your notice. This county has not published this year's values yet, so we estimate yours from last year's roll (shown as an estimate) unless you enter the value on your notice. You decide and file yourself.

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A $106,300 reduction

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Megan HollisHomeowner
Filing fee
$30
Where to file first
Sonoma County Assessment Appeals Board
Office address
575 Administration Drive, Suite 100-A, Santa Rosa, CA 95403 · (707) 565-2241
Our coverage
Free check available
  • Independent guide — not affiliated with Sonoma County or any government agency.
Last updated
October 1, 2026
Sources last checked
October 1, 2026
Status
Verified guide

How we verify facts

When and where do I file a Sonoma County property tax appeal?

Who hears a Sonoma County appeal?

One stage. We are not affiliated with this office.

Who hears it: Sonoma County Assessment Appeals Board

Filing: appeal

Open now

Where is the Sonoma County office?

Office[5]

Board of Supervisors (Assessment Appeals)

Address
575 Administration Drive, Room 100 A, Santa Rosa, CA 95403

Sonoma County Assessment Appeals Board[3]

Address
575 Administration Drive, Suite 100-A, Santa Rosa, CA 95403

Assessor[7]

Sonoma County Assessor's Office

Address
585 Fiscal Drive, Room 104F, Santa Rosa, CA 95403
Hours
Mon-Tue 8:00 AM-5:00 PM; Wed 8:00 AM-4:00 PM; Thu-Fri 8:00 AM-5:00 PM

We are not affiliated with this office. Hours can change, so call before you visit.

Which Sonoma County filing windows are coming up?

Sonoma County filing windows
ClosesAreaWho hears itStatus
Nov 30, 2026CountywideSonoma County Assessment Appeals Board · Official source · Last checked Sep 29, 2026Open now

When were past Sonoma County deadlines?

Past Sonoma County filing windows
Tax yearWindowOffice
2025Closed December 1, 2025Sonoma County Assessment Appeals Board
2024Closed December 2, 2024Sonoma County Assessment Appeals Board
2023Closed November 30, 2023Sonoma County Assessment Appeals Board

When is the deadline to appeal a property tax assessment in Sonoma County?

The soonest deadline we list: Sonoma County, Sonoma County Assessment Appeals Board — Closes November 30, 2026.

Deadline detailSonoma County Assessment Appeals Board · Filing period
Sonoma County's regular appeal filing period is July 2 to November 30.[1]

Who decides a property tax appeal in Sonoma County?

The Sonoma County Assessment Appeals Board's decision is final and not reheard; the owner or the Sonoma County Assessor may seek review in superior court. Sonoma County Assessment Appeals Board: In Sonoma County the filing is an assessment appeal on the Assessment Appeal Application (BOE-305-AH), heard by the Sonoma County Assessment Appeals Board.

Appeal stepsSonoma County Assessment Appeals Board
The Sonoma County Assessment Appeals Board's decision is final and not reheard; the owner or the Sonoma County Assessor may seek review in superior court.[2]
What the appeal is calledSonoma County Assessment Appeals Board
In Sonoma County the filing is an assessment appeal on the Assessment Appeal Application (BOE-305-AH), heard by the Sonoma County Assessment Appeals Board.[2]

How do I file a property tax appeal in Sonoma County?

Sonoma County Assessment Appeals Board: In Sonoma County you download the paper Assessment Appeal Application or ask the Assessment Appeals Board for a copy. Sonoma County Assessment Appeals Board: Sonoma County publishes its own copy of the Assessment Appeal Application (BOE-305-AH) with filing instructions.

How to fileSonoma County Assessment Appeals Board
In Sonoma County you download the paper Assessment Appeal Application or ask the Assessment Appeals Board for a copy.[3]
FormsSonoma County Assessment Appeals Board
Sonoma County publishes its own copy of the Assessment Appeal Application (BOE-305-AH) with filing instructions.[2]
Filing feeSonoma County Assessment Appeals Board
Sonoma County's appeal application carries a $30 non-refundable processing fee, paid when you file.[2]
Who may fileSonoma County Assessment Appeals Board
On the Sonoma County application, an agent must be authorized in writing unless the agent is a California attorney or the owner's spouse, child, parent or registered domestic partner.[2]
Informal reviewSonoma County Assessment Appeals Board
Sonoma County's informal Prop 8 review period for the 2026-27 assessment has closed; you can still file an appeal from July 2 to November 30.[4]
HearingsSonoma County Assessment Appeals Board · Schedule
Sonoma County's Assessment Appeals Board 2026 hearing calendar runs roughly monthly (e.g. October 2, November 6 and December 4, 2026), and the wait for a hearing is about 6-18 months.[5]

Upcoming appeal deadlines in every county we track

What evidence counts in Sonoma County, and can the value go up?

What evidence can I use in Sonoma County?

Sonoma County Assessment Appeals Board: Sonoma County's instructions ask for comparable sales, cost and income data, where relevant, to support the owner's opinion of value. Sonoma County Assessment Appeals Board · Exchange: Before a Sonoma County hearing, the owner may ask for an exchange of information with the Assessor; above $100,000 of assessed value the Assessor may start one.

Evidence acceptedSonoma County Assessment Appeals Board
Sonoma County's instructions ask for comparable sales, cost and income data, where relevant, to support the owner's opinion of value.[2]
Evidence ruleSonoma County Assessment Appeals Board · Exchange
Before a Sonoma County hearing, the owner may ask for an exchange of information with the Assessor; above $100,000 of assessed value the Assessor may start one.[2]

Can my assessment go up if I appeal in Sonoma County?

Sonoma County Assessment Appeals Board: Sonoma County's appeal instructions say the Sonoma County Assessment Appeals Board can raise, lower or keep the assessment, depending on the hearing evidence.

Can the value go up?Sonoma County Assessment Appeals Board
Sonoma County's appeal instructions say the Sonoma County Assessment Appeals Board can raise, lower or keep the assessment, depending on the hearing evidence.[2]

Which exemptions can lower my bill without an appeal?

Sonoma County homeowners may qualify for the Homeowner Exemption.

Homeowner exemption
Sonoma County homeowners may qualify for the Homeowner Exemption.[6]

What do Sonoma 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 Sonoma County property taxes?

Tax rate used: 1.139% of assessed value (county average, fiscal 2024-25).

How much could a lower assessment save on Sonoma County property taxes?
ExampleTax saved
$10,000 less assessed value$114 a year
10% less on a home assessed at $301,687 (the county's 25th percentile)$344 a year
10% less on a home assessed at $512,940 (the county's median)$584 a year
10% less on a home assessed at $755,000 (the county's 75th percentile)$860 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 Sonoma County pay in property tax?

The median owner-occupied home in Sonoma County was worth $815,500, and the median property tax its owners paid was $5,695 a year, according to the Census Bureau's American Community Survey.

Median home value
$815,500
Margin of error ±$6,412.
Median property tax paid per year
$5,695
Margin of error ±$106.
Median tax as a share of median value
0.70%
A ratio of two medians, not a tax rate. Your own bill depends on your assessment and local levies.
Owner-occupied homes
119,598
Margin of error ±1,666.

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.

From the county's assessment and appeal records

Homes in the county's assessment records
136,720
Median assessed value
$512,940
Middle half of assessed values
$301,687 to $755,000

Source: The county's open assessment data, aggregated by us (tax year 2025 final values). Our calculation from public records; not an opinion of any home's value.

How Sonoma County home assessments are spread

Assessed values of 136,720 homes in the property classes our free check covers (CND, MH, R24, R5, SFR), tax year 2025 final values. Half are between $301,687 and $755,000; the median is $512,940. The last bar holds everything above it.Source: Assessment records from the county's open data (tax year 2025 final values), retrieved Sep 27, 2026; our calculation.

Median home value: Sonoma County compared

  1. Sonoma County$815,500
  2. Typical California county$481,100
  3. Typical US county$185,300

Sonoma County $815,500; Typical California county $481,100; Typical US county $185,300

Census survey medians for owner-occupied homes. "Typical" is the middle county of the 58 in California and of all US counties.Source: U.S. Census Bureau, American Community Survey 5-year estimates, table B25077.

Median property tax paid: Sonoma County compared

  1. Sonoma County$5,695
  2. Typical California county$3,294
  3. Typical US county$1,619

Sonoma County $5,695 a year; Typical California county $3,294 a year; Typical US county $1,619 a year

Census survey medians for owner-occupied homes. "Typical" is the middle county of the 58 in California and of all US counties.Source: U.S. Census Bureau, American Community Survey 5-year estimates, table B25103.

Median home assessment by map book

  1. Map book 064$1,149,360
  2. Map book 139$1,129,587
  3. Map book 079$1,106,608
  4. Map book 020$1,086,425
  5. Map book 053$1,080,266
  6. Map book 090$1,009,499
  7. Map book 126$1,004,380
  8. Map book 110$953,871
  9. Map book 070$301,231
  10. Map book 095$284,200
  11. Map book 081$275,631
  12. Map book 105$274,743
  13. Map book 107$265,832
  14. Map book 041$240,361
  15. Map book 075$214,200
  16. Map book 106$210,115

The 8 highest and 8 lowest of 146.

Median assessed value by map book: highest Map book 064 ($1,149,360), lowest Map book 106 ($210,115).

Median assessed value of homes in the property classes our free check covers (CND, MH, R24, R5, SFR) for each map book with at least 50 such homes, tax year 2025 final values.Source: Assessment records from the county's open data (tax year 2025 final values), retrieved Sep 27, 2026; our calculation.

Sonoma County filing windows on a calendar

  1. Sonoma County Assessment Appeals BoardNov 30, 2026 · Open now

The dashed line marks today.

Sonoma County Assessment Appeals Board: Nov 30, 2026

Each bar is a filing window from its opening day to its last day. Forecasts show the expected closing range and are not official dates.Source: the official calendars and rules cited in the sources list below.

How often is property reassessed in Sonoma County?

In Sonoma County a new base year value is set when a property is sold, changes ownership or has new construction. Supplemental: In Sonoma County a supplemental assessment follows a reassessment after a change in ownership or new construction.

Reassessment cycle
In Sonoma County a new base year value is set when a property is sold, changes ownership or has new construction.[4]
Reassessment cycleSupplemental
In Sonoma County a supplemental assessment follows a reassessment after a change in ownership or new construction.[1]
Valuation date
Sonoma County compares values as of January 1, the lien date, for each tax year.[4]
Level of assessmentDecline in value
Sonoma County taxes most real property at the lower of its inflation-adjusted base year value and its fair market value on January 1.[4]

Homes in Sonoma 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
1979
All housing units, owned and rented
Single-family houses, detached or attached
75%
of 207,699 housing units
Owned homes with a mortgage or similar loan
66%
of 119,598 owner-occupied homes

Home values reported by owners

  1. Less than $50,0001%
  2. $50,000 to $99,9992%
  3. $100,000 to $199,9993%
  4. $200,000 to $299,9992%
  5. $300,000 to $399,9993%
  6. $400,000 to $499,9995%
  7. $500,000 to $749,99926%
  8. $750,000 to $999,99930%
  9. $1,000,000 to $1,999,99922%
  10. $2,000,000 or more6%

Home values reported by owners in Sonoma County: Less than $50,000 1%; $50,000 to $99,999 2%; $100,000 to $199,999 3%; $200,000 to $299,999 2%; $300,000 to $399,999 3%; $400,000 to $499,999 5%; $500,000 to $749,999 26%; $750,000 to $999,999 30%; $1,000,000 to $1,999,999 22%; $2,000,000 or more 6%.

Share of owner-occupied homes in each value range. Owners give this value in the survey; it is not the assessed value.Source: U.S. Census Bureau, American Community Survey, 2020–2024 5-year estimates, table B25075.

Property taxes owners pay a year

  1. No real estate taxes4%
  2. Less than $8004%
  3. $800 to $1,4995%
  4. $1,500 to $1,9993%
  5. $2,000 to $2,9998%
  6. $3,000 or more76%

Property taxes owners pay a year in Sonoma County: No real estate taxes 4%; Less than $800 4%; $800 to $1,499 5%; $1,500 to $1,999 3%; $2,000 to $2,999 8%; $3,000 or more 76%.

Share of owner-occupied homes by the real estate taxes paid in a year, with or without a mortgage.Source: U.S. Census Bureau, American Community Survey, 2020–2024 5-year estimates, table B25102.

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 Sonoma County property tax appeals

When is the Sonoma County property tax appeal deadline?

The Sonoma County Assessment Appeals Board window closes November 30, 2026.[8][9]

Is there a fee to file a property tax appeal in Sonoma County?

Sonoma County's appeal application carries a $30 non-refundable processing fee, paid when you file.[2]

Where do I file an assessment appeal in Sonoma County?

In Sonoma County you download the paper Assessment Appeal Application or ask the Assessment Appeals Board for a copy.[3]

Can my assessed value go up if I appeal in Sonoma County?

Sonoma County's appeal instructions say the Sonoma County Assessment Appeals Board can raise, lower or keep the assessment, depending on the hearing evidence.[2]

What other rules apply in Sonoma County?

Sonoma County Assessment Appeals Board: Filing a Sonoma County appeal does not postpone the tax bill: taxes are still due by the dates on the bill.

Paying the tax while you appealSonoma County Assessment Appeals Board
Filing a Sonoma County appeal does not postpone the tax bill: taxes are still due by the dates on the bill.[2]

Which details are not confirmed yet?

We show a fact only after a person has checked it against the official source. These are still being checked. Until then, ask the Sonoma County Assessment Appeals Board:

  • When a filing counts as on time

Property tax guides for Sonoma County homeowners

Counties next to Sonoma County

California property tax appeals: all counties

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Where do these facts come from?

  1. [1]Common Assessment Types and Filing Deadlines | Assessment Appeals | Board of Supervisors Department | Sonoma CountyOfficial guide or FAQ · last checked Sep 29, 2026
  2. [2]Assessment Appeal Application (BOE-305-AH) with instructions (Sonoma County, PDF)Official notice, form, calendar or rules · last checked Sep 29, 2026
  3. [3]Filing an Application | Assessment Appeals | Board of Supervisors Department | Sonoma CountyOfficial guide or FAQ · last checked Sep 27, 2026
  4. [4]Value Decline | Assessor | Sonoma CountyOfficial guide or FAQ · last checked Sep 29, 2026
  5. [5]Assessment Appeals | Board of Supervisors Department (County of Sonoma)Official guide or FAQ · last checked Oct 1, 2026
  6. [6]Property Tax Savings | Sonoma County AssessorOfficial guide or FAQ · last checked Sep 29, 2026
  7. [7]Welcome to the Assessor's Office | Assessor | Clerk-Recorder-Assessor (County of Sonoma)Official guide or FAQ · last checked Oct 1, 2026
  8. [8]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
  9. [9]Publication 30: Residential Property Assessment Appeals (California State Board of Equalization, February 2020)Official guide or FAQ · last checked Sep 25, 2026
  10. [10]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
  11. [11]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
  12. [12]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
  13. 13.County open data: sonoma assessmentsRetrieved Sep 27, 2026; aggregated by us for the charts above.
  14. 14.County open data: sonoma assessmentsRetrieved Sep 27, 2026; aggregated by us for the charts above.
  15. 15.U.S. Census Bureau, ACS 2020–2024 5-year estimates, table B25077: Median value (dollars), owner-occupied housing units — Sonoma County, California
  16. 16.U.S. Census Bureau, ACS 2020–2024 5-year estimates, table B25103: Median real estate taxes paid, owner-occupied housing units — Sonoma County, California
  17. 17.U.S. Census Bureau, ACS 2020–2024 5-year estimates, table B25003: Tenure (owner- and renter-occupied housing units) — Sonoma County, California

Data credits: Sonoma County data, CC BY-SA 3.0 · Census ACS (public domain) · Census county adjacency (public domain)

Not affiliated with Sonoma County or any government agency. Not legal advice. Not an appraisal.

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