Shoppers in Burlingame already pay a 9.625% sales tax rate. Hillsborough residents pay 9.375%. Both exceed the statewide average by more than two percentage points, and they could climb again after November 3, 2026.
The Connect Bay Area transit measure officially qualified for the November 2026 ballot the week of July 13, adding a half-cent sales tax across San Mateo, Alameda, Contra Costa and Santa Clara counties. If voters approve it, Burlingame's combined rate would rise to 10.125% and Hillsborough's to 9.875%.
The measure would be the sixth transit-related sales tax layered onto purchases in San Mateo County, according to the San Mateo Daily Journal. Revenue would largely cover operating deficits at Caltrain ($75 million average annual shortfall) and BART ($376 million), even as SamTrans projected a $13 million surplus for fiscal year 2025-26.
How the county's existing taxes add up
California's statewide base rate is 7.25%. On top of that, San Mateo County administers five voter-approved add-ons: Measures A, W and RR plus the San Mateo County Transit District tax fund road repairs, bike infrastructure, highway projects, Caltrain and SamTrans service. Measure K pays for affordable housing, emergency operations and healthcare.
State law caps local add-ons at 2% above the base, but San Mateo County exceeds that through state-granted exemptions. Municipal finance expert Michael Coleman told the Daily Journal that agencies routinely seek those waivers: "Up to 2% is the starting place of the law, but in many locations, when they are bumping up against that 9.25%, an agency goes to the state and asks for its rate to be exempt."
In May 2026, the San Mateo County Board of Supervisors voted 3-2 to sponsor legislation that would raise the maximum local sales tax cap by another half-percent, according to official meeting minutes.
Voter fatigue and the affordability question
San Mateo County Supervisor Ray Mueller warned that stacking tax measures erodes public trust. Mueller told the Daily Journal that another transit-dedicated tax cuts into city and county revenue opportunities and that some of the money would flow to agencies with surpluses or agencies that don't serve all taxpayers.
A poll reported by the San Francisco Chronicle showed 56% of voters supporting the Connect Bay Area measure. That's below the 60% cushion proponents typically seek. The measure needs only a simple majority to pass because it qualified as a citizen's initiative under SB 63, a 2025 state law that expanded initiative rules for regional transit measures.
More taxes on the same ballot
San Mateo and San Carlos are also considering local sales tax measures for the November 2026 ballot, the Daily Journal reported. County leaders have discussed asking voters to extend Measure A again in 2028.
Three statewide propositions on the same ballot would tighten rules on local tax measures if approved, according to CalMatters. One would require a two-thirds vote for taxes that qualify via signature-gathering, one would prohibit new personal property taxes, and a third would mandate audits of programs funded by new taxes.
