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Assessor Maps

What are Assessment/Assessor Parcel Maps

The Assessor establishes and maintains a set of maps for every tax parcel in the County for assessment purposes. These maps serve as the basis for assessment of all real property in Sonoma County.

In Sonoma County, there are more than 1,800 assessor’s maps, representing almost 187,500 parcels of land. These maps cover the entire county, including all cities and unincorporated areas.

Assessor maps show the assessor’s parcel numbers for the tax parcel, which may or may not be the same as the legal lot. Legal lot information can be found on official maps of record or recorded deeds which are available at the County Recorder’s Office.

Being based on recorded documents, the assessor parcel maps may not match what is seen or measured in person on the ground or what is seen on various map overlays and/or aerial photographs.  Assessor Maps are NOT surveys and should not be used in defining property lines. The Assessor's office mapping staff is always available to answer your questions about how your property is mapped and numbered for assessment purposes.​

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Accessing an Assessment/Assessor Parcel Map Online

You can view the current Assessor Parcel Maps via the online Assessor Portal. For historical assessors maps, please contact the Mapping Division at 707-565-1888 or assessor@sonoma-county.org.

  1. Find the property by searching by Fee Parcel (APN), Assessment Number or Street Address.
    1. If entering Street Address, enter the number and street name only. Do not enter the street suffix, such as Drive, Dr, Street, St, etc.
  2. Click on the property you are interested in viewing
  3. Select View Maps

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Other Map Information

For information on official recorded maps or documents, please contact the Sonoma County Clerk-Recorder. The Recorder’s Office has various types of maps, including records of survey and subdivision maps, as well as recorded deeds and easements. Click here to learn more about recorded maps.

For information on land use and zoning or for starting the process for easements, lot line adjustments, voluntary mergers, parcel maps, or corner records, please contact the Sonoma County or local City planning department.

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Frequently Asked Questions


Other Mapping Unit Duties

Combination of tax parcels.

  • Under certain circumstances, the Assessor’s office may be able to combine assessor’s tax parcels. Please click here for a list of considerations that will be reviewed before this can be approved. This list is not all inclusive but represents the primary criteria.
  • If you would like to get more information regarding this process, please contact our office at 707-565-1888 or assessor@sonoma-county.org.

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