The assessed value of properties in one of the nation’s most expensive regions continued to grow over the last year. The data is used to calculate property taxes and was released last week by the San Mateo County Assessor’s Office.
Atherton and Woodside had the fourth- and fifth-highest percentage increase in assessed value in the county at 6.49% and 6.4%, respectively. Atherton added approximately $1 billion in assessed value and Woodside added $574 million.
Atherton, ranked 16th of 20 cities in population within San Mateo County, has some of the nation’s most valuable land and is ninth in assessed value within the county. For comparison, Atherton has over $17.4 billion in assessed value, while Daly City, which has a population 14 times larger, has $18 billion in assessed value.
While Woodside and Atherton saw some of the largest percentage growth, Menlo Park had the fifth-largest nominal growth in assessed value, increasing by $1.1 billion to a total of $29.7 billion.
The 2025-26 assessment roll reflects values as of Jan. 1, 2025. San Mateo County assessed value increased 4.8%, down from 5.75% last year. While statewide data is not currently available, other counties are seeing less growth. Santa Clara County assessed value increased 4.15% and Marin County values increased 4.28%.
This is the 15th consecutive year of assessed value growth in San Mateo County and the 14th consecutive year of the county reaching record high assessed value.
Although assessed values increased, cities receive only a small portion of property taxes, which are calculated based on assessed value. Of the county’s 1% property tax on assessed value, cities typically receive 15%. Some cities may receive additional funds from bonds or parcel taxes approved by voters.
Since Proposition 13 passed in 1978, assessed value can only increase by a maximum of 2% annually unless the property is reassessed due to new construction or a transfer of ownership. Under Proposition 8, also passed in 1978, assessed values can decrease temporarily if home values decline to reflect market conditions. Menlo Park had one of the highest percentages of properties qualifying under Proposition 8, at 3.3%. The 285 parcels lost a combined $163 million in value. This reduction is temporary; if property values rise again, the assessed values can increase more than 2% to match market values, provided the properties no longer qualify under Proposition 8. Due to the decrease, Menlo Park lost $240,000 from its share of the 1% property tax.
A significant property tax gain for Menlo Park came from the sale of the USGS campus to Presidio Bay Ventures in April. The USGS, a federal government entity, previously paid no property taxes. Now, as the property is privately owned, taxes will be assessed based on the $130 million sale price, as first reported by this news organization.
The city will receive an additional $195,000 from the county’s 1% property tax due to the sale. However, it will only receive a prorated amount of the property tax from the date Presidio Bay closed on the property. The property was not included in this year’s assessor rolls as the sale occurred after January 1. The property alone accounts for a .44% growth in assessed value.
Unincorporated areas in the county, which include parts of west Menlo Park, Ladera, North Fair Oaks, saw a 5.15% increase in assessed value. In those areas, absent any agreement to the contrary, the county receives an additional 16% of property taxes instead of a city.
In 2024, unincorporated west Menlo Park had an assessed value of $2.8 billion this news organization learned through a Public Records Act request.
