In 1978, California voters passed Proposition 8, a constitutional amendment that allows a temporary reduction in assessed value when real property suffers a decline in value. A decline in value occurs when the current market value of real property is less than the current assessed (taxable) factored base year value as of the lien date, January 1.

Real property may decline in market value from one lien date to the next lien date; however, it will not benefit from a lower assessment unless its market value falls below the current factored base year value.  The decline in value is typically temporary and may be the result of changes in the real estate market, the neighborhood, or the property itself.

Please see the following example for more details. Check out the full version of the Fact Sheet here.


Request an Informal Assessment Review

(single family dwellings, residential condominiums, townhouses, live-work lofts and cooperative units only)
From January 2 to March 31 of each year, the Assessor will accept requests to review the market value of your property. You must submit your written request either online or in-person at our office, with supporting evidence of your opinion of value. If you were granted a temporary reduction for the preceding year, we will automatically review the assessed value for the next tax year.  A Notification of Assessed Value will be sent to you in July, which will indicate our findings. For more information, please read our Fact Sheet on Informal Review here

File an Assessment Appeal

(All property types)
If you disagree with the Assessor’s findings, you may file an Assessment Appeal Application with the Assessment Appeals Board (AAB), an independent body established to hear and resolve valuation disputes between the Assessor’s Office and property owners from July 2 through September 15 of each year. A non-refundable filing fee is due at the time of application and a hearing will be scheduled for you by the AAB at a later date. An Assessment Appeal Application and filing fee information may be obtained by contacting the Assessment Appeals Board – Clerk of the Board:

1 Dr. Carlton B. Goodlett Place
City Hall, Room 405
San Francisco, CA 94102
Phone: (415) 554-6778

For more information, please read our Fact Sheet on Assessment Appeal here.

Market value is the price a property would sell for when it is put up for sale in a competitive and open market.
The Assessor is required to enroll the lesser of your factored base year value (assessed value) or the market value. For example, if the market value of your property (what you could sell your house for) as of January 1st lien date is $500,000 and your assessed value is $600,000, the Assessor would enroll the $500,000 as your taxable value for that year only.

You will need to submit sales information and/or an appraisal performed by a licensed real estate appraiser to support your claim. The sales information or appraisal’s date of valuation should be as close to the January 1st lien date as possible, but no later than March 31st of the year under appeal.

It depends. If you owned the property for a while but have filed an appeal because you believe the market value has dropped for a particular year (i.e., a “Decline in Value” appeal), then the reduction is temporary and only applies to the tax year being appealed (referred to as a “Prop 8” reduction). If it is a Supplemental Assessment appeal, or an appeal against the property’s base year assessment, the new assessment has an ongoing impact. Please keep in mind it will still increase by no more than 2% per year under State law (Prop 13) until there is a change in ownership or new construction activity.
Unlike residential condominiums and cooperative units, TICs do not have separate parcel numbers. A review of a single TIC unit is more complex. TIC owners can appeal their property assessed values by filing an Application for Changed Assessment with the Assessment Appeals Board beginning July 2 through September 15 each year.
Property owners will be notified of the results of their informal assessment review in the annual Notice of Assessed Value which will be mailed at the end of July each year.

Under State law, we consider the market value of your property as of January 1 each year and compare it to your property's Proposition 13 (1978) protected value.  If the market value is lower than the Prop 13 protected value, we grant a temporary reduction for that year.  


The January 1, 2020 value ( which was before the COVID-19 local declared emergency and shelter-in-place order) is used to set your December 2020 and April 2021 property tax bills (mail out by the Office of the Treasurer and Tax Collector in October).  Generally we would not expect COVID-19 to impact your January 1, 2020 value because the emergency orders occurred after that date.  However, there could be an impact on property values when we next value properties on January 1, 2021.  If you believe the market value of your property is lower than your Prop 13 value on January 1, 2021, you will have the opportunity to formally appeal it to the Assessment Appeals Board ( between July 2, 2021 and September 15, 2021.

A temporary property tax reduction is not automatic.  The Assessor will review all submitted data and reductions may be granted depending upon the results of the market data.

Yes, a Letter of Authorization is required and must specify the Agent is authorized to represent the taxpayer in property tax assessment matters for the January 1, 2021 lien date.

One request is sufficient but be sure to identify all parcels that make up the economic unit.

It will show on your Notification of Assessed Value as a temporary reduction.  Notices are mailed from our office in July.

You may file for a hearing with the Assessment Appeals Board during the regular filing period.

If you are an owner of a house or condo, you are welcome to apply for an Informal Review.  

The survey is for commercial properties, while the Informal Review is for residential properties.  The survey data will be looked at in aggregate to identify market changes that support temporary value reductions, while Informal Reviews look at individual properties.

Any information you submit to us is required to be kept confidential and will not be made available for public inspection.

The Assessor’s Office wants to proactively engage with businesses and taxpayers to determine the extent the pandemic has eroded Real Property values for commercial properties. If we are able to find evidence of a market decline, we may be able to temporarily reduce property values under Proposition 8 (1979).

To inform this effort, we invite owners to participate in this Pandemic Market Survey.

By completing this survey and providing your data, you will help us understand current market conditions, their effect on property values, and potentially determine if your property has declined in value. Your confidential information will be kept secure and not shared outside our office.

How to fill out Market Survey:

  1. Click on the appropriate property type below to find your downloadable survey.
  2. Complete the survey and gather requested electronic documentation, if applicable.
  3. Email the survey document and other attachments to:
  4. Deadline to submit survey: March 31, 2021
Apartment Click to download Survey
Hotel Click to download Survey
Office Click to download Survey
Retail Click to download Survey


If you receive a temporary reduction, it will show on your Notice of Valuation that will be mailed from our office in July 2021. If you complete the survey and still do not agree with your January 1, 2021 valuation, you will be able to file a formal appeal with the Assessment Appeals Board.