Homes in Belmont are taxed at the statewide base rate of 1% of assessed value set by Proposition 13, plus voter-approved bond measures and local charges that bring the Belmont property tax rate to roughly 1.1% to 1.25% for most parcels. The exact figure depends on which tax rate area your home sits in, and the San Mateo County Controller publishes an annual Property Tax Rate Book listing the rate for every area in the county.
What Makes Up the Rate Above 1%
Proposition 13, passed in 1978, capped the general property tax levy at 1% of assessed value statewide.1California State Board of Equalization. California Property Tax An Overview Everything above that 1% in Belmont comes from voter-approved bonds for school districts, the community college district, and local services. These add-ons change as bonds are issued and retired, which is why the total rate drifts slightly each fiscal year.
Your annual bill also carries direct assessments as separate line items for things like sewer service, library funding, and mosquito abatement. Some Belmont subdivisions sit inside Mello-Roos Community Facilities Districts, which tack on a fixed annual charge on top of the ad valorem taxes. If you’re buying, ask the seller or your agent whether the parcel carries any Mello-Roos obligations. Those charges don’t appear in the percentage rate and can add hundreds or thousands of dollars a year.
How Your Assessed Value Is Set
The rate only matters once you know what it’s applied to. The San Mateo County Assessor establishes a “base year value” when a property changes ownership, and in most cases that value equals the purchase price.2San Mateo County Assessor-County Clerk-Recorder & Elections – ACRE. Change In Ownership From that point on, the assessed value can rise by no more than 2% per year, regardless of what the market does around you.3San Mateo County Assessor-County Clerk-Recorder & Elections – ACRE. How We Assess the Value of Your Property
Over time this creates a wide gap between neighbors. A home bought in 2005 for $700,000 might have an assessed value well under $1 million today, even if comparable Belmont homes are selling for $1.8 million. The long-time owner pays based on the lower figure. A new buyer gets reassessed at whatever they paid, which usually means a much larger tax bill for the same house.
If the market falls and your home’s fair market value on January 1 drops below your factored base year value, the Assessor must temporarily reduce your assessed value under Proposition 8. When the market recovers, the value can rise back toward the factored base year value without the 2% cap applying, but it can never exceed what the base year value would have been with normal annual increases.4San Mateo County Assessor-County Clerk-Recorder & Elections – ACRE. Property Tax Relief
New construction triggers a separate reassessment, but only on the part that was added or improved. The Assessor values the new work and adds it to the existing base. The original structure’s assessed value stays put.
The Supplemental Bill After You Buy
New Belmont owners are often blindsided by a supplemental tax bill arriving months after closing. When ownership changes, the Assessor reassesses the property at its new market value, and the difference between the old assessed value and the new one generates a supplemental assessment covering the remainder of the fiscal year (July 1 through June 30). A closing in October produces a supplemental bill for roughly nine months at the higher value.
You may actually get two supplemental bills: one for the remainder of the current fiscal year and a second for the following year if the regular tax roll hasn’t yet been updated. These are separate from your annual secured tax bill and carry their own due dates. Because they can take months to arrive, set aside funds at closing. When a property’s assessed value jumps sharply from what the prior owner paid, the catch-up amount is substantial.
Exemptions That Lower Your Bill
Several programs can cut what you owe, but none are automatic. You have to apply.
Homeowners’ Exemption
Living in your Belmont home as your primary residence qualifies you for a $7,000 reduction in assessed value.5California Department of Tax and Fee Administration. Homeowners’ Exemption At a combined rate around 1.2%, that’s about $84 off your annual bill. Modest, but free money if you file. Submit Form BOE-266 to the San Mateo County Assessor. It’s a one-time filing, and the deadline for the full exemption is February 15 of the assessment year.6Taxes. Property Tax Function Important Dates
Disabled Veterans’ Exemption
Veterans with a service-connected disability rated by the U.S. Department of Veterans Affairs get a far larger break. For 2026, the basic exemption reduces assessed value by $180,671, and the low-income exemption reduces it by $271,009 for households under a specified income limit.7California Department of Tax and Fee Administration. LTA 2025/014 – Disabled Veterans’ Exemption Increases for 2026 Both figures adjust annually for inflation. File Form BOE-261-G with the Assessor along with your VA rating decision letter by the same February 15 deadline.8California Department of Tax and Fee Administration. Disabled Veterans’ Exemption
Proposition 19 Base Year Value Transfers
Homeowners who are at least 55, severely disabled, or victims of a wildfire or natural disaster can transfer the taxable value of a current primary residence to a replacement home anywhere in California, usable up to three times.9California Department of Tax and Fee Administration. Prop 19 Base Year Value Transfer Guidance Questions and Answers The replacement must be purchased or built within two years of the sale and claimed as your primary residence. If the new home costs the same or less than the old one sold for, your tax base carries over unchanged; if it costs more, your base equals the old assessed value plus the difference in market values. You must file within three years of buying the replacement to get retroactive relief.
Parent-to-Child Transfers
Proposition 19 also governs transfers of a family home between parents and children, under tighter rules than the old law. The child must move in as a primary residence within one year of the transfer and file for the homeowners’ or disabled veterans’ exemption in that same window. The exclusion from reassessment is capped at the existing taxable value plus $1,044,586 (the figure for transfers between February 16, 2025, and February 15, 2027). Value above that threshold gets reassessed at current market rates. File Form BOE-19-P with the Assessor within three years of the transfer.10California Department of Tax and Fee Administration. Proposition 19 Fact Sheet
Challenging an Over-Assessment
If you think the Assessor overvalued your home, you have two paths. First is an informal decline-in-value review: contact the Assessor’s office and present evidence that your fair market value on January 1 was below the assessed value. The deadline to request this informal review for the 2026 assessment year is October 31, 2026.4San Mateo County Assessor-County Clerk-Recorder & Elections – ACRE. Property Tax Relief
If that doesn’t resolve it, file a formal appeal with the San Mateo County Assessment Appeals Board. For regular 2026 assessments, the filing window runs July 2, 2026, through November 30, 2026.4San Mateo County Assessor-County Clerk-Recorder & Elections – ACRE. Property Tax Relief Bring hard evidence: recent sale prices of comparable Belmont homes, a professional appraisal, or documentation of conditions that reduce market value. Appeals that tie a specific dollar figure to concrete comparables carry far more weight than general objections.
Payment Deadlines and Penalties
San Mateo County splits property taxes into two installments. The first installment covers July through December and is due by December 10. The second covers January through June and is due by April 10. If a deadline lands on a weekend or holiday, it moves to the next business day.11County of San Mateo, CA. Tax Collector
Miss December 10 and a 10% penalty hits the next day. Miss April 10 and the penalty is 10% plus a $40 cost.11County of San Mateo, CA. Tax Collector On an $8,000 installment, one day late costs an extra $800. There is no grace period and no forgiveness for mailing delays.
Payment options include free eCheck through the county’s online portal (available until 11:59 p.m. Pacific on the delinquency date), credit card online with a 2.35% service fee, mail (postmark controls), and in-person payment at the county office in Redwood City.12County of San Mateo, CA. Using the Tax Payment System For most people, eCheck is the clear choice: no fee and immediate confirmation.
If You Don’t Pay
Unpaid property taxes become a lien on the property, and penalties and interest keep accruing. After five years of tax default, the property is subject to sale by the county tax collector at public auction to satisfy the debt.13State Controller’s Office. Public Auctions and Bidder Information That timeline shortens to three years when the property also carries a nuisance abatement lien. A tax lien also clouds your title, which can make refinancing or selling impossible until the balance is cleared. If you’re struggling, call the San Mateo County Tax Collector early. Payment arrangements are easier to set up before default advances.
Deducting Belmont Property Taxes Federally
Property taxes are deductible on your federal return only if you itemize.14Internal Revenue Service. New and Enhanced Deductions for Individuals For 2026, the standard deduction is $32,200 for married joint filers, $16,100 for single filers, and $24,150 for heads of household.15Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 Itemizing only pays off when your deductible expenses exceed those thresholds.
Even then, the SALT deduction covering state income taxes, local taxes, and property taxes combined is capped at $40,400 for most filers in 2026, or $20,200 for married filing separately. Given Belmont property values and California income tax rates, many homeowners hit that cap well before all their deductible taxes are counted. The cap was raised from $10,000 by the One Big Beautiful Bill Act signed in July 2025, with small annual increases scheduled through 2029.