July 5, 2022

Contact: Mark Church, Chief Elections Officer & Assessor-County Clerk-Recorder
Alternate: Jim Irizarry, Assistant Chief Elections Officer & Assessor-County Clerk-Recorder
Alternate: Terry Flinn, Special Assistant to the Assessor

(Redwood City, CA) San Mateo County Assessor Mark Church today announced the County’s Property Assessment Roll increased year-over-year by $22.2 billion, or 8.34%, to a record high of over $288.0 billion in assessed value. 

“2021 marked yet another record year of Roll growth for San Mateo County,” said Church. “Similar to 2020, this year’s increase was again largely due to record-setting single family home values driven by strong demand for homes that continued as we came out of the pandemic. Moreover, commercial values have also recovered significantly and contributed to the increase.”

The combined Assessment Roll has increased by $145.5 billion from twelve years ago. This is the twelfth consecutive year in which a new historical high has been set. The Secured portion of the Roll, which is approximately 96.3% of the total Roll and primarily consists of real property, increased in value by 8.37%. The Unsecured portion makes up the remaining 3.7% of the total Roll and increased in value by 7.36%. The Unsecured Roll includes business assets such as commercial airline property at SFO and business property in leased locations throughout the County. 

“The growth rate in sales for single family homes again saw a substantial increase of 34.4%, making 2021 another year of strong growth for residential properties, with a strong rebound of 54.4% growth in the condominium and townhome segment of the market,” said Church. “Residential properties contributed over $13 billion to the 2022-23 Assessment Roll increase,” added Church.

Additionally, the record increase can be attributed to the continued recovery from the pandemic. As the restrictions gradually lifted, businesses began to re-open and air travel resumed. “The Unsecured Roll bounced back to a strong growth along with the Secured Roll,” added Church.

The Bay Area had some of the highest business closure rates in the nation during the height of the pandemic in 2020, according to data from Yelp. However, according to the Bureau of Labor Statistics, the Bay Area has regained 75.8 percent of the jobs it lost at the outset of the widespread business shutdowns at the start of the pandemic in March and April of 2020.

According to the Employment Development Department (EDD), unemployment in San Mateo County, home to strong technology and life sciences industries, has decreased to 1.7%, as of May 2022, making it the lowest unemployment rate in the State of California.  In total, 33,500 jobs have been regained in the County since December 2020. San Mateo is one of nine counties which significantly contribute to the economy of the San Francisco Bay Area as an urban center, according to the EDD. Our diverse economic base contributes to a favorable long-term outlook.

Highlights of the 2022 Roll

The 2022-23 Property Assessment Roll reflects overall growth throughout the County. Total assessed values increased in all 20 cities and unincorporated areas, with increases ranging from 5.24% to as high as 12.64%, and an overall increase of 8.34%.  The County’s unincorporated areas, which include San Francisco International Airport (SFO), returned to a positive growth rate of 6.82%, primarily due to resurgence of business activity at the Airport. Commercial Airline assessments, that had seen a decrease in 2020, declined by another 14%.

The top 5 cities with the highest percentage growth in Assessed Value are:​

  • San Carlos (+12.64%)
  • South San Francisco (+12.53%)
  • Burlingame (+10.77%)
  • Millbrae (+9.43%)
  • East Palo Alto (+9.29%)

The top 5 cities with the highest dollar growth in Assessed Value are:​

  • South San Francisco - $3.08 billion
  • San Mateo - $2.59 billion
  • Redwood City - $2.08 billion
  • Menlo Park - $1.85 billion
  • San Carlos - $1.74 billion

The assessed value increases in these 5 cities total over 51% of the Roll increase for the 2022-2023 Roll.

The property tax revenue generated is approximately 1% of the annual property Assessment Roll and this year will increase to $2.88 billion. Approximately 45% of the revenue will go to schools within the county, 25% to the County, 18% to cities, 10% to special districts, and 2% to former redevelopment agencies. “The County’s share will be 25%, or approximately $720 million, an increase of $55 million over last year,” noted Church. 

The Property Assessment Roll is the assessed value of all properties as of January 1 each year, and reflects changes in ownership, new construction, value declines, and value restorations from the previous January 1. The Property Assessment Roll is composed of two sections, the Secured Roll and the Unsecured Roll.  When combined, the two sections are referred to as the Combined Roll.


The Secured Roll represents over 96% of the Combined Roll and includes 222,350 commercial, residential, and agricultural real properties.  This year, the Secured Roll increased to $277 billion, an increase of $21.4 billion or 8.37% over 2021-22, reflecting continued economic growth in the County.  

The growth of the San Mateo County Secured Roll is primarily due to the following factors:

New Commercial Development. “Commercial and mixed-use construction were among the major contributors to the Roll’s significant growth,” noted Church. “Major projects in the County, consisting of 80,000 square feet or more, accounted for more than 6.6 million square feet of new development coming to market in 2021.”

In all, 64.6 million square feet of new construction are expected to be completed in the County over the next six to eight years. A total of 9.12 million square feet are under construction, 13.9 million square feet have planning approval, and 41.6 million square feet are under review. Approximately 17 million square feet of new construction have been completed in the last five years.

Commercial projects account for 58.33% of all major construction projects being tracked by the Assessor’s office. The following table shows the percentages attributed to each of the major use-types in the County’s development pipeline.

New Major Development​

Life Science 22.73%
Office 20.62%
Master Planned Community 8.12%
Senior Care Facility 1.65%
Hotel 1.56%
Retail 1.38%
Industrial Park 1.16%
Hospital 0.88%
School 0.23%


Commercial Sq. Ft. 58.33%
Residential Sq. Ft. 20.81%
Mixed Use 20.86%
Grand Total 100%

Top 5 Cities for New Commercial Development. The following cities have the greatest amount of major development, consisting of projects that are 80,000 square feet or more that are pending, approved, or under construction:

  • Redwood City – 22.1 million square feet
  • South San Francisco – 16.7 million square feet
  • Menlo Park – 11.4 million square feet
  • Brisbane – 8.2 million square feet
  • San Mateo – 4.9 million square feet

“Growth in the technology and life science sectors continues to drive the demand in office, housing, lodging and retail,” said Church.

Completed commercial projects in 2021 include Meridian 25 Life Science and office complex in San Carlos, and Gateway of Pacific Life Science project in South San Francisco, with over 1.3 million square feet of commercial development completed in these projects.

Residential completions were led by Station Park Green in San Mateo. Other apartment complex projects completed include the Summer Hill Apartments in Burlingame and Greystar IV in Redwood City, with a combined total of over 1.9 million square feet of residential development completed in these projects.

Sales and Ownership Changes. Sales and changes in ownership totaled $11.6 billion, or about 54% of this year’s Secured Roll increase of $21.4 billion.  Residential sales accounted for about 77% of that dollar growth while commercial sales accounted for 23%.

According to the San Mateo County Association of Realtors (SAMCAR), median sales prices of single-family homes in San Mateo County increased by 11.68% in 2021 to $1,898,500, as compared to the median price of $1,700,000 in 2020. Total dollar value of sales increased significantly by 51.06% and the number of sales also significantly increased by 34.4% for the calendar year. Residential values are at a record high, so when residential property is re-assessed at market value due to a change in ownership, the new value can be substantially higher than the previous assessment. These price-level changes account for the substantial impact residential reassessments have on Roll growth overall.

Prop 19: Impact on the Assessed Values. In November 2020 California voters approved Proposition 19 which made two significant changes in California property tax law.

  1. It created more restrictions to the use of intergenerational transfers that qualify for exclusion from reassessment between parents and their children and between grandparents and grandchildren. Intergenerational transfers are now restricted to a property that is designated by the transferee child or grandchild, as use for their principal residence; and
  2. It changed the criteria for property owners over the age of 55 who wished to transfer the assessed value from one principal residence to a replacement principal residence. This provision took effect on April 1, 2021. It allows a transfer of a lower property tax base from any county in California, and if a property owner purchases a more expensive replacement principal residence, the assessed value in excess of one million dollars is transferred with an adjustment.

The impact of these new regulations on assessed values are now reflected in our 2022 Assessment Roll. The 2021 Assessment Roll included 93 base year transfers, of which one-third were transfers from outside of San Mateo County. Base year transfers reflected in our 2022 Assessment Roll doubled to 200 transfers, with 35% from outside of San Mateo County.

Restoration of Assessed Value: Proposition 8/Decline in Value Program. The Proposition 8/Decline in Value Program provides property tax relief to property owners when the market value of a property falls below its assessed value. The number of residential properties qualifying for the Proposition 8/Decline in Value Program decreased by 25%, from 392 in FY 2021-22 to 294 in FY 2022-23, which is significantly below the record high of 34,700 properties in FY 2011-12. On the commercial side, a pro-active review program to identify COVID-19 affected properties was initiated in 2020. In another sign of recovery, the number of commercial properties that qualified for property tax relief decreased by 14%, from 132 in 2020 to 114 in 2021, a number still substantially below the high of 604 properties in FY 2012-13.

Over the next few days, more than 294 residential property owners enrolled in the program will be mailed their FY 2022-23 Assessed Value Notices, with 73 being fully restored to their factored base year (Prop 13) values.

Annual Inflation Factor. Proposition 13, which governs property taxation in California, ties the annual inflation factor to the California Consumer Price Index (CCPI) issued by the California Industrial Relations Board and limits annual inflation increases to no more than 2%. This year an annual inflation factor of 2% was applied to the FY 2021-22 assessed value of all real property that did not have a change in ownership or any new construction during 2021.

Recorded Foreclosures. There were 18 Trustee’s Deeds recorded in calendar year 2021, a 50% increase from the 12 recorded in 2020.  Notices of Defaults on the other hand, further decreased 15% from 174 in 2020 to 148 in 2021, continuing the downward trend in defaults since the high of 5,058 in 2009. 

“Recorded foreclosure activities are still low despite a slight increase in numbers, another important indicator of the strength of the local economy,” said Church.


The Unsecured Roll comprises approximately 4% of the Property Assessment Roll and includes the valuations of business/personal property, air transportation related property at SFO and possessory interests (leased government property).  This year, the Unsecured Roll increased to $10.7 billion in assessed value, an increase of $0.7 billion or 7.36% over the prior year’s Unsecured Roll.  This increase is primarily coming from Biotech and Life Science companies, Possessory Interest Assessments as airports open, and some key business accounts like Facebook.

Commercial Airline assessments continue to decrease and were down another 14% in 2021. Most of the Unsecured Roll is business or personal property, which typically depreciates and is not subject to an annual inflationary value increase, as is real property on the Secured Roll.   


2022-23 Local Combined Roll
2022-23 Local Secured Roll
2022-23 Local Unsecured Roll
2022-23 Residential Decline in Value Summary

Related Contacts

Mark Church

Assessor-County Clerk-Recorder and Chief Elections Officer
555 County Center
Redwood City, CA 94063-1665Get Directions

Jim Irizarry

Asst. Assessor-County Clerk-Recorder & Asst. Chief Elections Officer
555 County Center
Redwood City, CA 94063-1665Get Directions

Terry Flinn

Special Assistant to the Assessor