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Prop 13

How California's Proposition 13 sets your property tax: the 1% levy, base year value, the 2% annual cap, reassessment when you buy, and a calculator for your factored base year value and tax.

Updated November 4, 2026. Free, no sign-up; everything runs in your browser and nothing you type is stored.

Prop 13 property tax calculator

Purchase price / base year value ($)Year you bought (base year)Tax yearYearly inflation factor (%, max 2)Voter-approved rates on top of 1% (%)Current market value ($, optional)Exemptions on your bill ($, e.g. homeowners' exemption)

Estimated yearly property tax

–

–Factored base year value

–Assessed value

–Tax at full market value

What Prop 13 does

Proposition 13 (1978) limits California property tax to 1% of assessed value, plus voter-approved taxes for local bonds and schools. Assessed value starts at the base year value: the 1975 value, or the purchase price or new-construction value after that. Each year the base year value can rise by inflation, but by no more than 2% (Santa Clara County Assessor). A change in ownership or new construction resets the base year value to market value.

Example: a home bought in 2016 for $500,000 has a 2026 factored base year value of about $609,497 at 2% a year. At 1% plus 0.15% of voter-approved taxes (Sacramento County says local bonds bring its average to about 1.1%), the tax is about $7,009, even if the home is now worth $900,000.

Prop 8: when market value falls

If market value drops below the factored base year value, the assessor can temporarily enroll the lower value (Prop 8). The factored base year value keeps rising up to 2% a year behind the scenes, so the assessed value can increase by more than 2% in a year as the market recovers, up to that limit.

Prop 13 and buying or inheriting

Buying a home sets a new base year value at the purchase price. Transfers between parents and children are limited by Proposition 19 (2021); check with your county assessor before transferring property. For tax on other homes, use the property tax calculator.

Common questions

What is Prop 13?

California's 1978 law limiting property tax to 1% of assessed value plus voter-approved taxes, with assessed value rising at most 2% a year until a sale or new construction.

How much can my California property tax go up each year?

The assessed value can rise by up to 2% a year, plus any change in voter-approved rates.

Does Prop 13 reset when you sell?

Yes. A change in ownership resets the base year value to the market value.

What is a factored base year value?

The base year value increased each year by inflation, up to 2%; it's the upper limit of your assessed value.

Sources

More mortgage and home calculators: Conventional Loan · How to Get Pre Approved for a Home Loan · USDA Home Loan · 50 Year Mortgage Calculator

General information, not financial, tax or legal advice. Check important numbers with the official source before acting on them.