San Mateo County assessment roll reaches $357.6B as major projects cluster in three cities

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San Mateo County’s Assessor-County Clerk-Recorder published the 2026–27 assessment roll with a countywide total of $357.6 billion and a secured roll of $344.5 billion. That represents 4.85% year-over-year growth for the total roll and 5.14% growth for its secured portion.

The release also identifies the cities with the largest dollar increases in assessed value and shows where major commercial projects—defined as projects of at least 80,000 square feet—are concentrated across the Peninsula.

San Mateo County assessment roll: the key numbers

• Countywide totals: The assessment roll reached $357.6B; the secured roll reached $344.5B.
• Top city growth by dollars: Menlo Park added $2.07B, San Mateo $1.55B, Redwood City $1.24B, Atherton $1.17B, and Burlingame $1.15B.
• Large-project concentrations: Redwood City accounts for approximately 21.15M square feet, South San Francisco 19.43M, Menlo Park 13.68M, Brisbane 8.27M, and Burlingame 7.22M.
• Recent completions: The county highlighted Elco Yards in Redwood City, Bay Meadows Station 1 in San Mateo, Peninsula Innovation Point in Burlingame, and an expansion of the Primary School campus in East Palo Alto.

Why it matters for Peninsula commercial real estate

1. Tax and revenue assumptions. Roll growth is an early countywide signal that feeds municipal revenue forecasts and informs property-tax projections used in underwriting and pro forma stress tests. City finance teams will fold these totals into budget updates and capital planning.
2. Development geography. The catalogue of large projects provides a practical map of where sizable supply is clustered. Redwood City, South San Francisco, and Menlo Park together represent a substantial share of the Peninsula’s large-floorplate pipeline, making those markets especially important for competitive leasing and absorption analysis.
3. Portfolio implications. Investors and lenders should reconcile assessed-value growth with the market-value drivers visible in recent sales and leasing. Faster assessed growth can signal demand while also creating near-term tax exposure for owners.
4. Local comparables. The named completions provide concrete reference points for rent, operating-cost, and valuation benchmarking in their submarkets.

What We’re Watching

Watch how city budget teams translate the roll into revenue forecasts, capital priorities, and infrastructure spending. Owners should also map their competitive sets against the county’s large-project inventory and revisit property-tax assumptions before the next underwriting update.

Sources & Documents

• San Mateo County Assessor-County Clerk-Recorder — 2026–27 assessment roll release (primary source)