How Property Tax Is Calculated in California
California property tax is your assessed value × your Tax Rate Area's rate, minus exemptions, plus any fixed charges. The assessed value is your Proposition 13 base-year value (normally the price you paid) grown by at most 2% a year; the rate is the statewide 1% levy plus the voter-approved bonds where you live. Below is each step with a worked example on a real Tax Rate Area.
Quick answer: on an $800,000 purchase in a typical Alameda County Tax Rate Area taxed at 1.1741%, the first full year's bill is about $9,311 after the $7,000 Homeowners' Exemption — $8,000 for the 1% base levy plus $1,393 for voter-approved bonds, less $82 for the exemption — before any Mello-Roos or direct charges.
Step 1: Assessed value (Proposition 13)
When a property changes hands, the county assessor sets its base-year value at the purchase price (its market value on that date). Each year after, the value rises by the statewide inflation factor — the California CPI change, capped at 2% — until the next change of ownership or new construction. That compounded number is the factored base-year value, and it is what the tax is calculated on. Market value after you buy does not matter unless it drops below the factored value, in which case Proposition 8 allows a temporary reduction.
Worked example — bought in 2016 for $600,000
Applying the official factors for 2017-18 through 2026-27 (the first roll after the purchase) gives a factored base-year value of about $724,484 for the 2026-27 roll — up 21% over 10 years, whatever the home would sell for today. The factor for 2026-27 is 2.000%; the full history is on the inflation-factors page.
A buyer skips this step: the assessed value is simply the purchase price. See owner vs. buyer for why the two numbers can differ so much on identical homes.
Step 2: The tax rate — 1% plus voter-approved bonds
Proposition 13 caps the general levy at 1% of assessed value. On top of it, each Tax Rate Area (TRA) adds the rates needed to repay the general-obligation bonds its voters approved — school, community college, hospital, transit, park and water bonds. The county Auditor-Controller publishes every TRA's stack in its annual rate book. Here is a real one: Fremont's most common TRA (012013) in Alameda County for 2025-26, applied to an $800,000 assessed value.
| Levy (agency) | Rate | On $800,000 |
|---|---|---|
| Countywide 1% levy (Proposition 13) | 1.0000% | $8,000 |
| Fremont Unified school bonds | 0.0908% | $726 |
| Ohlone Community College bonds | 0.0276% | $221 |
| Washington Township hospital district | 0.0218% | $174 |
| BART (Bay Area Rapid Transit) bonds | 0.0152% | $122 |
| County general-obligation bond | 0.0084% | $67 |
| Alameda County Water District | 0.0060% | $48 |
| City of Fremont bonds | 0.0032% | $26 |
| East Bay Regional Park District | 0.0011% | $9 |
| Total ad-valorem rate | 1.1741% | $9,393 |
Source: Alameda County Auditor-Controller tax rate book, FY 2025-26, TRA 012013. Rates differ by TRA — the county's ZIPs run from about 1.1% to 1.3% — so look yours up on the rate-by-county page or your county's explorer, and never assume a flat 1%.
Step 3: Subtract exemptions
The Homeowners' Exemption takes $7,000 off the assessed value of an owner-occupied home (Revenue & Taxation Code § 218) — worth about $82 a year at 1.1741%. Larger exemptions exist for disabled veterans and certain nonprofit uses; there is no general senior exemption in California. On the example above the first-year bill becomes $9,311. How to claim the Homeowners' Exemption →
Step 4: Add direct charges and Mello-Roos
Everything above is ad valorem — based on value. Your bill then lists flat amounts that are not: fixed direct assessments (sewer, lighting, landscaping, mosquito abatement, school parcel taxes, each a set dollar amount per parcel) and, in newer communities, a Mello-Roos special tax for a Community Facilities District, often several hundred to a few thousand dollars a year. These vary parcel by parcel, which is why two bills at the same assessed value and rate can still differ. What the direct charges on a California bill look like →
Step 5: The purchase year — supplemental bills
The regular bill for the year you buy was set on the previous owner's value. The county catches up with a supplemental bill for the difference between the old and new assessed value, prorated for the months left in the fiscal year (July–June), and a second one if you bought between January and May. Use the supplemental property tax calculator for the amount and timing.
Step 6: Two installments
The annual secured bill is paid in halves: the first installment is due November 1 and delinquent after December 10, the second due February 1 and delinquent after April 10, with a 10% penalty after each date. Dates, mailing and penalties are on the due-dates calendar.
Put it together
Purchase price (or prior base-year value × annual factors, ≤ 2%/yr) = assessed value − exemptions ($7,000 Homeowners' Exemption) × Tax Rate Area rate (1% + voter-approved bonds, e.g. 1.1741%) = ad-valorem tax + fixed direct assessments + Mello-Roos (flat amounts, parcel-specific) = annual secured bill, paid in two installments
Run your own numbers with the California property tax calculator (statewide county averages), or the ZIP-level calculators for Los Angeles, Orange, San Diego and Sacramento counties.
Manufactured and mobile homes: same arithmetic, two tax systems
A manufactured home first sold new on or after July 1, 1980 is taxed exactly like the house above: the county assessor sets a base-year value when it is sold, the value rises at most 2% a year, the $7,000 Homeowners' Exemption applies to an owner-occupant, and the Tax Rate Area rate is applied to the result (Revenue and Taxation Code §5800 and following). The home is assessed separately from the land: in a mobilehome park the space is assessed to the park owner, so a resident's bill covers the home only. A home first sold before July 1, 1980 stays on the state Department of Housing and Community Development's in-lieu vehicle license fee instead, unless its owner has voluntarily converted it to local property tax, a choice that cannot be reversed.
The Board of Equalization counts 307,250 manufactured homes on California county rolls in 2025-26, assessed at $25.9 billion together — an average of $84,254 each, against $51,098 in 2015-16. At a 1.15% rate the average home's ad-valorem tax is about $888 a year after the Homeowners' Exemption. The counties with the most on the roll:
| County | Manufactured homes on the roll | Average assessed value |
|---|---|---|
| Riverside | 47,471 | $85,010 |
| Los Angeles | 26,436 | $46,963 |
| San Diego | 26,208 | $157,510 |
| Orange | 23,822 | $23,567 |
| Kern | 22,340 | $75,339 |
Source: Board of Equalization Table E2, assessors' roll statistics (2025-26; 47 counties reporting). Homes still on the HCD in-lieu fee are not on the roll and are not counted. Assessed value is the Proposition 13 roll value, not a sale price.
Frequently Asked Questions
How is property tax calculated in California?
Assessed value × tax rate, minus exemptions, plus any direct charges. The assessed value is your Proposition 13 base-year value (usually the price you paid) grown by at most 2% a year. The rate is the 1% statewide levy plus the voter-approved bonds of your Tax Rate Area — typically 1.05%–1.25% in total. Exemptions such as the $7,000 Homeowners' Exemption come off the assessed value, and fixed direct charges and any Mello-Roos special tax are added as flat amounts.
Is California property tax based on purchase price or market value?
Purchase price, in effect. Under Proposition 13 a change of ownership resets the assessed value to the price paid (its market value on that date). After that the county does not reassess to market each year; the value rises by the annual inflation factor, capped at 2%, until the next sale or new construction. Market value matters again only if it falls below the factored value, when Proposition 8 lets the assessor temporarily lower it.
What is the Proposition 13 inflation factor for 2026-27?
2.000% — the California CPI change for the year was above 2%, so the 2% cap applies (BOE Letter to Assessors 2026/002). The factor has been below 2% in only a few years, most recently 1.036% in 2021-22.
Why does my neighbor pay a different property tax on a similar house?
Two reasons. Assessed value: an owner who bought in 2005 is taxed on a 2005 price grown by at most 2% a year, while a 2024 buyer is taxed on the 2024 price. Rate: homes in different Tax Rate Areas carry different voter-approved bonds, so the rate can differ by a few hundredths of a percent even on the same street, and a parcel inside a Mello-Roos district pays a special tax a neighbor outside it does not.
How is property tax calculated on a mobile home in California?
It depends on when the home was first sold. A manufactured home first sold new on or after July 1, 1980 is on the local property-tax roll: the county assessor sets a Proposition 13 base-year value when it changes hands, it rises at most 2% a year, the $7,000 Homeowners' Exemption applies if you live in it, and the bill is the Tax Rate Area rate (about 1.1%–1.25%) on that value — the same arithmetic as a house. A home first sold before July 1, 1980 instead pays an annual in-lieu vehicle license fee to the state Department of Housing and Community Development, unless the owner voluntarily converted it to local property tax (a one-way choice). The land under a space in a mobilehome park is assessed to the park owner and recovered through rent. In 2025-26, 307,250 manufactured homes were on California's county rolls at an average assessed value of $84,254.
Does the 1% rate include school bonds?
No. The 1% is the Proposition 13 base levy, shared among the county, cities, schools and special districts under state allocation rules. Voter-approved general-obligation bonds — school, community college, hospital, transit, park and water bonds — are added on top as separate rates in your Tax Rate Area, which is why a typical California rate is 1.1%–1.2% rather than exactly 1%.
How do I find my exact tax rate?
Your county Auditor-Controller publishes a rate book listing every Tax Rate Area and its levies, and your tax bill prints your TRA number. This site's county explorers list each TRA's levies by agency for 57 counties, and the ZIP pages give the typical rate and range for your ZIP code.
Learn More
Educational explainer, not tax advice. The example levies are the Alameda County Auditor-Controller's FY 2025-26 rates for one Tax Rate Area; your own TRA, exemptions and direct charges set your bill. Confirm figures with your county Assessor, Auditor-Controller and Treasurer-Tax Collector.
Last reviewed: October 2026.