Assessment and Real Property Valuation

Assessment Reviews

The Assessor's Office has a review program where taxpayers can ask the Assessor to take a closer look at the taxpayer's Property Tax Assessment.  Such requests can be made due to a Decline in Value based on market conditions or a more general Assessment Review asserting a change in value due to any cause.

Assessment Review requests are also referred to as Proposition 8 (or Prop 8) reviews.

History and Impact of Proposition 13

On June 6, 1978, California voters overwhelmingly approved Proposition 13, a property tax limitation initiative. This amendment to California’s Constitution was the taxpayers’ collective response to dramatic increases in property taxes and a growing state revenue surplus. Proposition 13 (or "Prop. 13") rolled back most local real estate assessments to 1975 market value levels, limited the property tax rate to 1 percent plus the rate necessary to fund local voter-approved bonded indebtedness, and limited future property tax increases to a maximum of 2% per year.

Prior to 1978, real property was appraised cyclically, with no more than a five-year interval between reassessments. Since property values were systematically reviewed and updated, assessed values were usually kept at or near current market value levels. In contrast, under Proposition 13, properties are reassessed to current market value only upon a change in ownership or completion of new construction (called the base year value). In addition, Proposition 13 generally limits annual increases in the base year value of real property to no more than 2 percent, except when property changes ownership or undergoes new construction. Essentially, Proposition 13 converted the market value-based property tax system to an acquisition value-based system.

Under Proposition 13, similar properties can have substantially different assessed values based solely on the dates the properties were purchased. Disparities result wherever significant appreciation in property values has occurred over time. Longtime property owners, whose assessed values generally may not be increased more than 2 percent per year, tend to have markedly lower tax liability than recent purchasers, whose assessed values tend to approximate market levels.

[Source: California State Board of Equalization, Publication 29.]

Notice of Supplemental Assessment

A Notice of Supplemental Assessment is generated whenever the assessed value of a property changes due to a change in ownership or the completion of new construction. Such reassessments may result in one or more Supplemental Tax Bills being mailed to the property owner. These Supplemental Tax Bills are in addition to the annual property tax bill. The Assessor mails Notices of Supplemental Assessment approximately 60 days before the supplemental tax bill is mailed by the Tax Collector's Office. 

For more information on Supplemental Property Taxes, please consult the Frequently Asked Questions (FAQs) below. Additional information is also available from the County Tax Collector.

Property Information Search

The Assessor has many instructive pamphlets to provide property owners with information on all subjects related to property assessment. The office also has building record and appraisal information for current property owners.

View property information search

Property Tax Assessed Values

The Assessor has assessment roll information that indicates the assessed value of every property in the County. We also have a list of transfers of real property generated each year.

Property Tax Forms

The County of SLO Assessor has over 65 forms and documents available for the public to access to complete a wide range of assessment-related business, including filing a Change of Address, a Homeowner’s Exemption, a Business Property Statement, or a Claim for a Disaster Relief.

Property Tax Postponement Program

The State Controller’s Property Tax Postponement Program allows homeowners who are seniors, are blind, or have a disability to defer current-year property taxes on their principal residence if they meet certain criteria including 40 percent equity in the home and an annual household income of $35,500 or less.

Applications are typically available in September and are funded beginning in October on a first come first served basis.  Please call (800) 952-5661 or go to, the State Controller's Office website for more information.

Property Use Report

A Property Use Report is used to report activity on exempt property and details of any use apart from the primary activity by outside groups or individuals.

Public Records Act Request

The California Public Records Act (CPRA) was passed in 1968 requiring inspection or disclosure of governmental records to the public upon request, unless they are exempt by law.