Property Tax in Burlingame and Hillsborough, CA

Proposition 13: The Framework Underneath Every Bill

California voters passed Proposition 13 in 1978, and it still sets the property tax structure for every parcel in the state, Burlingame and Hillsborough included. A property's assessed value is generally locked in at its purchase price at the time of sale, and it can then rise by no more than 2% per year regardless of how fast actual market value moves -- until the next change of ownership resets it to the new purchase price. In a market with genuinely old money like Hillsborough, that mechanic produces real, dramatic gaps: a family that bought an estate decades ago may be carrying an assessed value a fraction of what a comparable 2026 purchase would establish, while a new buyer resets to full current value the moment escrow closes.

The base rate is capped at 1% of assessed value at the state constitutional level, but actual bills run above a flat 1% almost everywhere in California because of voter-approved local add-ons -- city and county bond measures, school district bonds and parcel taxes, and occasionally Mello-Roos Community Facilities District assessments in newer developments. Which specific add-ons apply to a given Burlingame or Hillsborough parcel depends on its exact San Mateo County tax rate area, and the two towns can differ from each other and from their neighbors even a few blocks apart.

The San Mateo County Assessor and a Real, Sourced Rate

The San Mateo County Assessor-County Clerk-Recorder's office is the correct jurisdiction for both towns, and it's a genuinely active one: the county's 2025-26 local assessment roll reached a record $341.1 billion, its 15th consecutive year of growth, up 4.80% over the prior year, per the Assessor's own reporting. Ownwell's city-level effective-rate data cites a Burlingame-specific figure of 1.16% -- notably below the California statewide median of 1.21% and below the general San Mateo County range of roughly 1.25% to 1.26% that most county homeowners fall into. This page did not find that figure independently confirmed against a primary San Mateo County document and states it as a directional, aggregator-sourced number rather than a guaranteed rate for any specific parcel.

This page did not find a confirmed, Hillsborough-specific effective-rate figure distinct from the general San Mateo County range, and does not invent one; a reasonable planning assumption is the county-wide 1.25%-1.26% range absent a more specific number, though Hillsborough's unusual mix of very old, low-basis estate parcels next to recently resold ones at full current value may push its own effective average in either direction relative to that county figure.

Two Worked Dollar Examples

In real dollars: a Burlingame purchase at $2.7 million (near the middle of the roughly $2.5M-$2.9M 2026 price range covered on the Real Cost page) at the sourced 1.16% effective rate works out to a first-year property tax bill near $31,320. A Hillsborough purchase at $5 million, using the more conservative county-wide 1.25% rate absent a confirmed Hillsborough-specific figure, works out to roughly $62,500 per year. Both are illustrative rate-times-price calculations for planning purposes only -- not a substitute for the San Mateo County Assessor's own parcel-specific figure, which is the only number that should actually be used to budget a real purchase.

Why the Seller's Current Tax Bill Is the Wrong Number to Budget From

Because Prop 13 resets assessed value at every change of ownership, a seller's current property tax bill reflects whatever they paid -- possibly decades ago, possibly capped at 2% annual growth ever since. This matters more acutely in Hillsborough than almost anywhere else on this site: a longtime estate owner's tax bill, capped since a purchase in the 1980s or 1990s, can be a small fraction of what a 2026 buyer's own bill will be on the same property. A listing showing a seller's tax bill from decades ago tells a new buyer essentially nothing about their own future bill in either town. Budget from the actual purchase price times a realistic current effective rate -- 1.16% for Burlingame per the sourced figure above, or the more conservative county-wide 1.25%-1.26% range for Hillsborough absent a town-specific number -- not from whatever figure appears in the disclosures.

Prop 19 Portability and Exemptions

California's standard statewide rules apply the same way in both towns. A modest homeowner's exemption reduces assessed value for an owner-occupied primary residence -- a small dollar benefit against either town's price levels, but a real one. Proposition 19 (approved 2020, effective in phases from 2021) lets eligible homeowners age 55+, severely disabled homeowners, and wildfire or disaster victims transfer their existing, lower assessed value to a replacement home elsewhere in California, generally up to three times for age or disability-based moves -- a genuinely useful mechanic for a longtime California homeowner, including a Hillsborough estate owner, considering downsizing into a Burlingame home without a full reassessment at current purchase price. Prop 19 also narrowed the prior parent-child transfer exclusion, generally now requiring a child inheriting a home to use it as their own primary residence to keep the parent's lower assessed value -- a real, practical consideration for either town's longtime family-owned properties.

This page does not restate every Prop 19 eligibility rule; the San Mateo County Assessor's office maintains current forms and guidance and should be the first stop for anyone planning to use Prop 19 portability in connection with a purchase here.