California property tax is unlike almost anywhere else in the United States because of Proposition 13, the 1978 ballot measure that rewrote how the state assesses and taxes real estate. Where most states levy a market-value tax that rises and falls with the housing market, Prop 13 locks your assessed value to roughly the purchase price when you buy, caps the base levy at 1 percent, and limits annual assessment increases to the lesser of inflation or 2 percent. The result is a tax bill that is far more stable than the home itself — and that makes the bill very predictable to estimate.
This calculator applies the Prop 13 formula directly: a 1 percent base levy, plus the voter-approved bond and district rates that push the effective rate to roughly 1.1 percent statewide, projected forward with the 2 percent annual cap. Enter your assessed value, adjust the bond rate to match your county, and the calculator returns your annual tax, the monthly escrow amount, the effective rate, and a multi-year forecast under the Prop 13 growth cap.
How to Use
- Enter the Assessed Home Value. In California this is usually the purchase price on the day you closed escrow — not today's market value. If you have owned the home for years, your county assessor's Notice of Assessed Value shows the current figure; use that.
- Leave the Prop 13 Base Rate at 1.0 percent. This is the constitutional ceiling set by Proposition 13 and it applies to every county in the state. You only change it if you are modeling a special district that itself caps the base differently, which is rare.
- Set the Voted Bonds & Assessments add-on. The statewide average effective add-on is about 0.1 percent, but it ranges from roughly 0.05 percent in quiet counties to 2.5 percent or more in districts that approved large school bonds or Mello-Roos financing. Check your most recent property tax bill for the "direct assessments" line, or use 0.1 percent as a default.
- Adjust the Assessment Growth Cap if you know the inflation factor your county published. Prop 13 legally caps this at 2 percent per year; the actual factor is often 1.0–2.0 depending on the CPI. Leaving it at 2.0 gives the conservative (highest) projection.
- Choose the Projection Horizon — 1, 3, 5, or 10 years — to see how the capped assessed value and the resulting tax bill climb over time.
The result card breaks the annual tax into the 1 percent base and the bond/assessment add-on, converts the annual figure into a monthly escrow deposit, and shows the effective tax rate as a single percentage. The projection block shows the assessed value and tax in the final year of your horizon, plus the cumulative tax paid across the whole period.
The Prop 13 Formula
California property tax follows two simple equations. The annual levy in year one is:
Annual Tax = Assessed Value × (1% + local bond rate)
And the assessed value in later years is capped:
Assessed Value(t) = Assessed Value(0) × (1 + growth cap)^t
Where the growth cap is the lesser of the California inflation rate and 2 percent. The tax bill only jumps back to market value when the property changes ownership — that moment is called a "reappraisal" and it is why long-time California homeowners often pay a small fraction of what new buyers on the same street pay. This effect, called Prop 13's "welcome stranger" problem, is one of the most debated features of California housing policy.
Worked example on an $800,000 home with a 1.0 percent base and 0.1 percent bond add-on: the base tax is $8,000, the bond add-on is $800, and the total annual tax is $8,800, or about $733 per month escrowed. The effective rate is 1.1 percent. After five years at the 2 percent cap, the assessed value grows to about $865,946 and the annual tax climbs to roughly $9,525. Over those five years the homeowner pays about $45,796 in total property tax.
Examples
Example 1 — A buyer in Los Angeles. A couple closes on a $950,000 home in Los Angeles. The county assessor sets the assessed value at the purchase price, the base rate is 1.0 percent, and the combined school bond and community-services add-on is 0.18 percent. The annual tax is $950,000 × 1.18% = $11,210, or about $934 per month in escrow. Lenders will typically require this amount plus homeowner's insurance to be collected each month, so the escrow deposit is closer to $1,100.
Example 2 — A long-time owner in San Francisco. A homeowner bought in 1995 for $300,000. Under Prop 13 with the 2 percent cap, the assessed value has compounded to roughly $510,000 today, even though the home would sell for over $1.5 million. At a combined 1.15 percent rate the annual tax is about $5,865 — less than a third of what a new buyer on the same block would pay. This is the textbook Prop 13 scenario.
Example 3 — A high-value home in San Diego. On a $1,500,000 home with the default 1.0 percent base and 0.1 percent add-on, the annual tax is $16,500 and the monthly escrow is about $1,375. Because the assessed value resets to the purchase price at closing, the first-year bill is the largest the owner will see for as long as they hold the property.
FAQ
How is California property tax calculated?
California property tax is 1 percent of the assessed value (the Prop 13 base levy) plus any voter-approved bonds, school district charges, and Mello-Roos assessments in your area. The statewide average effective rate is about 1.1 percent. The assessed value starts at the purchase price and can rise only by the lesser of inflation or 2 percent per year until the home is sold.
What is Prop 13 and how does it affect my tax bill?
Proposition 13 (1978) is a state constitutional amendment that set the 1 percent base rate cap, required a two-thirds vote for local tax increases, and — most importantly — froze the assessed value near the purchase price with a 2 percent annual growth cap. It is the reason two otherwise identical California homes on the same street can carry very different tax bills depending on when each owner bought.
What is the average property tax rate in California?
The average effective California property tax rate is about 1.1 percent of assessed value. That breaks down to the constitutional 1 percent base plus roughly 0.1 percent in local bonds and assessments. Actual county rates range from around 0.7 percent in some rural counties to above 1.2 percent in counties with heavy school-bond debt.
Why is my property tax so much lower than my neighbor's?
That is the Prop 13 "welcome stranger" effect. Your neighbor likely bought decades ago at a much lower price, and their assessed value has grown only at the 2 percent cap. Your assessed value reset to today's purchase price when you closed escrow. The tax bill will equalize only when your neighbor sells and their home reappraises to market value.
Does California have a property tax deduction or exemption?
Yes. California offers a Homeowners' Exemption of $7,000 off the assessed value for a primary residence, which reduces the annual bill by roughly $70–$80 depending on your combined rate. There are also larger exemptions for disabled veterans and a postponement program for low-income seniors. Apply through your county assessor's office after closing.
How often do I pay California property tax?
California property taxes are billed twice a year, in two installments. The first installment is due November 1 and delinquent after December 10; the second is due February 1 and delinquent after April 10. If you have a mortgage, your lender usually collects one-twelfth of the estimated annual tax each month into an escrow account and pays the county on your behalf.
Can my assessed value ever fall below what I paid?
Yes. Under Proposition 8 (1978), if the market value of your home drops below its Prop 13 factored assessed value, the county assessor can temporarily reduce the assessment to the lower market value. When the market recovers, the assessment can climb back — but never above the original Prop 13 capped value.
Disclaimer
This California property tax calculator is provided for informational purposes only and does not constitute tax, legal, or real-estate advice. Estimates use the statutory Prop 13 1 percent base rate plus a user-entered local bond rate and the 2 percent annual assessment growth cap; actual bills depend on your county assessor's valuation, voter-approved debt, Mello-Roos districts, the Homeowners' Exemption, and any Proposition 8 reductions. Always confirm your official assessed value and tax amount with your county assessor's office and your annual property tax statement before making financial decisions.