Property taxes in Los Altos start with California’s 1% base rate on assessed value, then climb once voter-approved school bonds, community college measures, and water district parcel taxes are added on top. Most Los Altos homeowners see an effective rate above 1.2% of assessed value before flat per-parcel charges, and because home prices here are among the highest in California, the dollar amounts are substantial. The Santa Clara County Assessor sets your assessed value; the county Department of Tax and Collections handles the billing.
How the Bill Is Built
Proposition 13, passed in 1978, caps the base property tax rate at 1% of assessed value. Your assessed value starts as the purchase price when you buy, and that figure becomes your base year value.1Office of the Assessor | County of Santa Clara. Understanding Proposition 13 From there, the assessor can raise it by no more than 2% per year under Revenue and Taxation Code Section 51, no matter what the market does.2California Legislative Information. California Revenue and Taxation Code 51 This is why a neighbor who bought thirty years ago may pay a fraction of what the buyer of an identical home across the street pays today.
The 1% is only the starting point. Voter-approved bond measures and special parcel taxes stack on top, and the specific combination depends on which taxing districts cover your parcel. The quickest way to see exactly what applies to your property is to pull your bill through the Santa Clara County Department of Tax and Collections.
What Los Altos Homeowners Pay on Top of the 1%
Los Altos School District
LASD levies two parcel taxes that together run roughly $890 per parcel. The original tax, $597 per parcel with no sunset date, funds class sizes, teacher retention, and core programs. A second tax, Measure A, was approved in November 2023 at $295 per parcel for eight years with a 4% annual cost-of-living adjustment.3Los Altos School District. Los Altos School District – Parcel Tax Senior homeowners can apply for an exemption.
Foothill-De Anza Community College District
Measure G, an $898 million general obligation bond, adds roughly 1.6 cents per $100 of assessed value through the 2053–54 fiscal year. Measure H adds a flat $48 parcel tax for five years.4Foothill-De Anza Community College District. Ballot Measures G and H
Santa Clara Valley Water District
The Safe, Clean Water and Natural Flood Protection Program, approved in November 2020, charges a parcel tax based on parcel size rather than assessed value, so the amount varies.5Valley Water. Safe, Clean Water and Natural Flood Protection Program
Homeowners in the City of Los Altos and in unincorporated Los Altos Hills may see different totals depending on which benefit districts overlap their parcel.
When Your Assessment Resets
Buying a Home
A change of ownership resets the assessed value to the current fair market value. That new figure becomes your base year value, and the 2% annual cap starts fresh.6Santa Clara County Assessor. Glossary For buyers coming in at today’s Los Altos prices, this is the largest single jump most property owners ever see on a tax bill.
New Construction
Major renovations, additions, pools, and accessory dwelling units trigger a reassessment, but only on the value added by the new work. The existing portion of your home keeps its current assessed value and its 2% cap.7California State Board of Equalization. New Construction Routine maintenance and cosmetic work (paint, carpet) does not count as new construction and will not trigger a reassessment.
Supplemental Bills After a Purchase or Project
After a sale or completed construction, expect one or two supplemental tax bills in addition to the regular annual bill. These cover the gap between the prior assessed value and the new one, prorated for the months remaining in the fiscal year (July 1 through June 30).8California State Board of Equalization. Supplemental Assessment If the event happens between January and May, you’ll get two bills: one for the rest of the current year and one for the full next year. Events between June and December produce one. These arrive separately from your regular statement, have their own deadlines, and can total thousands of dollars. Watch the mail for several months after closing.
Payment Deadlines and Penalties
Santa Clara County splits the annual bill into two installments:
- First installment: due November 1, delinquent after 5:00 p.m. on December 10. A 10% penalty attaches immediately to the unpaid amount.9California Legislative Information. California Revenue and Taxation Code 2617
- Second installment: due February 1, delinquent after 5:00 p.m. on April 10. Same 10% penalty.10County of Santa Clara. Tax Bill and Collections
If a deadline falls on a weekend or county holiday, it moves to the next business day.11Department of Tax and Collections. Obtain Secured Property Tax Information There is no other grace period. On a $15,000 bill, missing a deadline costs $1,500.
If both installments remain unpaid, the property becomes tax-defaulted. A $15 redemption fee is added, and additional penalties accrue at 1.5% per month (18% annualized) on the unpaid balance. Continued default can eventually lead to a tax lien sale.
How to Pay
The county accepts payments online, by mail, by phone, and in person at the Department of Tax and Collections in San Jose.12Department of Tax and Collections. Pay Your Bill eCheck payments online are typically free. Credit and debit card payments carry a convenience fee of about 2.25%, which on a $10,000 installment runs around $225, so most homeowners paying large bills use eCheck or a mailed check. If you have a mortgage with an impound account, your servicer pays the county directly and will adjust your monthly payment when assessed value or special assessments change.
Exemptions and Relief Programs
Homeowners’ Exemption
If the Los Altos property is your primary residence, you can claim the homeowners’ exemption, which reduces assessed value by $7,000.13California Legislative Information. California Revenue and Taxation Code 218 At the 1% base rate that saves about $70 per year, plus a little more from bond-related ad valorem charges. You must occupy the home on the January 1 lien date, and you can’t combine it with a veterans’ exemption on the same property. File once with the Santa Clara County Assessor; it stays in effect until the home is no longer your primary residence.
Disabled Veterans’ Exemption
Veterans rated 100% disabled by the U.S. Department of Veterans Affairs (or who are blind in both eyes or have lost the use of two or more limbs due to service) qualify for a larger exemption: roughly $100,000 off assessed value under the basic version, and about $150,000 under the low-income version. Both figures are adjusted annually for inflation. Unmarried surviving spouses of qualifying veterans can also claim it.14California State Board of Equalization. Disabled Veterans’ Exemption
Proposition 19 for Older and Disabled Owners
Proposition 19 lets homeowners who are 55 or older, severely disabled, or victims of a governor-declared wildfire or natural disaster transfer their existing low assessed value to a replacement home anywhere in California. The benefit is available up to three times.15California State Board of Equalization. Proposition 19 If the replacement home costs more than the original, the difference between the two market values is added to the old base, so the transfer still produces meaningful savings even on a trade-up.
Property Tax Postponement
The California State Controller’s Property Tax Postponement Program lets homeowners who are seniors, blind, or disabled defer the current year’s taxes if household income is $55,181 or less and the home has at least 40% equity. The state records a lien, and the deferred amount is repaid later, typically at sale or death.16State Controller’s Office. Property Tax Postponement The filing window closes in early February, well before the April payment deadline.
Appealing Your Assessment
If the assessor’s valuation looks too high, start with a free informal review directly with the Assessor’s Office. If the assessor agrees, the value is corrected without any filing fees or hearings.17County of Santa Clara Clerk of the Board. Appeal Your Property Taxes
If that doesn’t resolve it, file a formal assessment appeal with the Clerk of the Board. As of June 2026, the nonrefundable filing fee is $290 for residential, vacant land, and agricultural properties, and $675 for commercial or multifamily properties with five or more units. Fee waivers are available for applicants receiving public assistance. Appeals can be filed online or in person at 70 West Hedding Street in San Jose.17County of Santa Clara Clerk of the Board. Appeal Your Property Taxes
The burden of proof is on you. The law presumes the assessor’s value is correct, so bring evidence: recent comparable sales of similar Los Altos homes, an independent appraisal, or documentation of problems that reduce market value, such as foundation issues or deferred maintenance. Arguing that taxes feel too high, or that a neighbor’s assessment went up less, won’t meet the bar. Try the informal route first; the $290 fee is nonrefundable whether you win or lose.