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COVID-19 Updates: Get the latest public information related to coronavirus disease 2019 (COVID-19) at

COVID-19 has changed some of the procedures for providing service to you. For most questions or concerns, please call our office at (805) 781-5643 or review our website. If you need to meet with assessor staff, video conferencing or appointments can be scheduled. Please call or email to schedule a meeting or video conference. Our office is open to the public; however, there may be wait times due to the requirements for social distancing (Per California of Public Health Guidance, face coverings need to be worn while in the building). Documents may also be mailed in or delivered using the public drop box located outside our office lobby. 

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County Seal

Assessor's Office

County of San Luis Obispo

Notice of Supplemental Assessment

Frequently Asked Questions

What is meant by change in ownership or new construction?

A change in ownership occurs when title to the property is transferred. Transfers can be triggered by the sale, inheritance or seizure of real property.

New construction includes any addition to real property or any substantial alteration to an existing structure. Such projects may or may not require a building permit.

Exclusions may be granted, but require the filing of documentation with the our office. See Exclusions for more information.

How do I read my Notice of Supplemental Assessment?

The Assessor determines a new value for the property whenever there is a change in ownership or completion of new construction. The Assessor then calculates the difference between the new value and the existing value. That difference is the Supplemental Assessment Value. Once the new assessed value of your property has been determined, the Assessor sends a Notice of Supplemental Assessment.


New value at date of change in ownership or completion of new construction  $ 220,000
Assessed Value for current fiscal year  $-200,000
Supplemental Assessment Value $    20,000

Supplemental Taxes are calculated based on the difference (increase or decrease) in value. As a result, one or more Supplemental Property Tax Bills will be issued. 

If the reassessment results in a decrease in value, a refund will be issued by the Auditor-Controller's Office. A decrease in value will not reduce the amount due on the annual tax bill. The annual tax bill must be paid in full before a refund can be issued.

Am I entitled to an exemption on my Supplemental Taxes?

You may be eligible for an Exemption on your Supplemental Tax Bill, which may result in a reduction of your property taxes. Applications for homeowner, veteran, church, welfare, or other exemptions may be obtained at our Property Exemption Information page.

Who should I call if I have questions about my Notice of Supplemental Assessment?

If you have questions about your Notice of Supplemental Assessment, please call our office at (805)-781-5643 and discuss the Notice with one of our appraisers. If you believe there is an error, or you disagree with the value, you may submit an Assessment Review Request to our office within 60 days of the mailing date shown on your notice.

Filing the Assessment Review Request does not protect your Assessment Appeal rights. Your Review Request should be filed as soon as possible to allow our office time to complete the review before the 60-day deadline for filing a formal Assessment Appeal.

For more information regarding Assessment Appeals, please see the Clerk-Recorder's website.