The Basic Formula: Assessed Value Times Tax Rate
California property tax is calculated by multiplying your property's assessed value by the tax rate set by your county. The assessed value is not what you paid for the house or what it's worth on the market — it's the value the county assessor assigns to your property, which is usually lower than market value. The tax rate varies by county and can range from about 0.6% to 1% of assessed value, depending on local bonds and special assessments in your area.
The formula looks like this: Assessed Value × Tax Rate = Annual Property Tax. If your home's assessed value is $500,000 and your county's tax rate is 0.75%, you would owe $3,750 per year in property tax.
Your property tax bill arrives once a year, usually in the fall, and covers taxes for the fiscal year that runs from July 1 to June 30. Most homeowners pay in two installments: one in December and one in April.
Key Takeaways
- Your assessed value is set by the county assessor and is usually much lower than what you paid for your home or what it would sell for today.
- Proposition 13, passed in 1978, limits how much your assessed value can increase each year — usually no more than 2% — even if your home's market value rises much faster.
- Your tax rate is set by your county and includes the base rate plus any voter-approved bonds or special assessments for schools, fire districts, or other services.
- You can challenge your assessed value through a formal appeal process if you believe the county assessor made an error or if your home's market value has dropped significantly.
How the County Assessor Sets Your Assessed Value
The county assessor's office determines your property's assessed value by looking at recent sales of similar homes in your area, the condition of your property, and any improvements you've made. They do not straightforward use your purchase price. If you bought your home for $600,000 but similar homes in your neighborhood are selling for $550,000, the assessor might set your value lower than what you paid.
When you first buy a property, the assessor typically sets the initial assessed value close to your purchase price. After that, the value can only increase by a maximum of 2% per year under Proposition 13, regardless of how much your home's actual market value grows. This is one of the biggest reasons California property taxes stay relatively stable for long-term homeowners — your assessed value grows slowly even if your neighborhood becomes much more expensive.
The assessor reassesses your property at full market value only when there is a change in ownership. If you inherit a home or receive it as a gift, the reassessment happens at that time. If you make major renovations or add a new structure, the assessor may increase the value of just that addition.
Understanding Your County's Tax Rate
The tax rate you pay is not a single number set by the state. Instead, it is built up from several layers: a base rate, plus rates for school districts, fire protection districts, water districts, and any voter-approved bonds or special assessments. Your county assessor's office publishes the combined rate for your specific property address, so two homes next to each other might have slightly different rates if they fall into different school or fire districts.
The base rate in California is set at 1% of assessed value by state law. On top of that, local agencies add their own rates. A typical combined rate might be 0.75% to 0.85% of assessed value, but this varies widely by location. You can find your exact tax rate on your property tax bill or by contacting your county assessor's office.
When voters approve a bond measure — for example, to fund school construction or fire equipment — that bond rate gets added to your tax bill for a set number of years. These are separate line items on your bill, so you can see exactly what portion of your tax goes to schools, what goes to the county, and what goes to special districts.
How Proposition 13 Affects Your Assessed Value
Proposition 13 is a 1978 law that fundamentally changed how California property tax works. It says that once a property is assessed, its value can increase by no more than 2% per year, even if the home's market value skyrockets. This protection applies until the property changes ownership, at which point it is reassessed at current market value.
This means a homeowner who bought a house 20 years ago may be paying tax on an assessed value far below what the home is actually worth today. For example, if you bought a home for $300,000 in 2004 and it is now worth $800,000, your assessed value might only be around $450,000 because of the 2% annual cap. You would pay tax on $450,000, not $800,000.
The 2% increase happens automatically each year on your bill — you do not need to do anything. The county assessor applies it whether your home improved or not. If your home's market value actually drops, you may be able to request a reduction in assessed value, which is discussed in the next section.
Challenging Your Assessed Value Through Appeal
If you believe your assessed value is too high, you can file a formal appeal with your county assessor's office. The most common reason to appeal is if your home's market value has fallen — for example, if you bought during a market peak and prices have since dropped in your area. You can also appeal if you believe the assessor made a factual error, such as miscounting the number of bedrooms or overstating the square footage.
The appeal process starts with a written request to your county assessor. You will need to provide evidence of the value you think is correct, such as recent appraisals, comparable sales in your neighborhood, or documentation of damage or defects. The assessor will review your evidence and either agree to lower the value or deny your request. If denied, you can appeal to the county Assessment Appeals Board, which is an independent body that hears disputes.
The important date to file an appeal is usually in late July or early August, before the tax year begins on July 1. Check your county assessor's website for the exact important date in your area, as it varies by county. Filing an appeal does not may provide a reduction, but it is your right if you have evidence that the assessed value is incorrect.
Special Assessments and Bonds on Your Bill
Beyond the base property tax, your bill may include charges for special assessments or voter-approved bonds. These are separate line items and are calculated differently than the regular tax rate. A special assessment might be a one-time or multi-year charge to pay for a specific improvement — for example, a new sewer line or street repaving in your neighborhood. A bond is a long-term debt that a local agency took on to fund a large project, and property owners in that district pay a portion of it through their tax bill.
Special assessments are usually charged per parcel or based on the size of your lot, not on your home's value. Bonds are typically charged as a percentage of assessed value, similar to the regular tax rate. Your bill will break down each charge separately so you can see what you are paying for. If you own property in multiple districts or if your property straddles district lines, you may see multiple assessment or bond charges.
These charges are mandatory if you own property in the district, and they do not go away until the bond is paid off or the assessment period ends. You cannot opt out of them.
Frequently Asked Questions
Why is my property tax bill so different from my neighbor's even though our houses look the same?
Your assessed values are likely different because you may have bought at different times or prices. Under Proposition 13, assessed value grows at only 2% per year, so a neighbor who bought decades ago pays tax on a much lower value than someone who bought recently. You might also be in different school or fire districts, which have different tax rates.
Does my property tax go down if my home's market value drops?
Not automatically. You have to file an appeal with your county assessor if you believe your assessed value is too high compared to current market value. The assessor will not lower it on their own just because prices fell in your neighborhood. You typically have until late July to file an appeal for the upcoming tax year.
What happens to property tax when I sell my house?
When you sell, the new owner's assessed value is reset to the purchase price (or market value if lower). The 2% annual increase cap starts over for them. Your tax liability ends on the date of sale, and the new owner becomes responsible for taxes starting on the next tax year.
Are there any deductions or exemptions that lower my property tax bill?
California offers some exemptions, such as for homeowners over 65 with limited income, disabled veterans, and certain nonprofit organizations. You must file a claim with your county assessor to receive an exemption. Homeowners who are not in a special category do not receive deductions — the Proposition 13 cap is the main protection against rising taxes.
How do I find out what my exact tax rate is?
Your tax rate is printed on your property tax bill. You can also contact your county assessor's office or visit their website and enter your property address. The rate shown will be the combined rate for your specific location, including all local districts and any voter-approved bonds.