The city of San Mateo gained roughly $1.55 billion in assessed property value over the past year, the second-largest dollar increase of any city in the county, according to a Patch summary of assessor data published July 9.
The gain is part of a countywide surge that pushed the total assessment roll to a record $357.6 billion for the 2026-27 fiscal year, a 4.85% jump over the prior year. County Assessor-County Clerk-Recorder Mark Church announced the figures on July 6, marking the county's 16th consecutive year of assessment roll growth.
The growth rate has cooled, though. The roll grew 8.34% in 2022; the past two years have been more modest, landing at roughly the same 4.85% pace.
Countywide, the new roll will generate an estimated $3.58 billion in property tax revenue, according to the assessor's office. About 51% of that, roughly $1.8 billion, flows to schools. Another 25% goes to the county, 16% to cities, 7% to special districts, and 1% to former redevelopment agencies.
New construction drove 61% of the $16.6 billion countywide increase. The assessor's office tracked 4 million square feet of major development projects in 2025, led by life science and office buildings.
Church said the office will monitor interest rates, housing affordability, and commercial real estate trends that could affect future rolls.
Prop. 8 relief for thousands of owners
Even as the overall roll climbs, many individual property owners are seeing lower tax bills. Of 7,400 properties the assessor's office evaluated for potential value declines, 6,572 qualified for a temporary Proposition 8 reduction because their assessed value exceeded their current market value. Those reductions total $3.5 billion countywide.
Proposition 8, approved by California voters in 1978 alongside Proposition 13, allows assessors to temporarily lower a property's taxable value when market conditions push it below the Prop. 13 baseline. The relief is automatic and temporary; values are restored as the market recovers.
The assessor's office attributed rising home values to AI-driven wealth in the tech sector, even as high mortgage rates have discouraged selling. The median sale price for a single-family home in San Mateo County reached $2,401,000 in May 2026, up 9.1% from $2,200,000 a year earlier, according to the California Association of Realtors.
What happens next
Property tax bills reflecting the new 2026-27 assessed values will be mailed to San Mateo County property owners later in 2026. The $3.58 billion in projected revenue will fund city services, the San Mateo-Foster City School District, and special districts across the county. Property owners who believe their assessment is incorrect can contact the assessor's office to request a review.
