California Property Tax

California assesses property on an entirely different principle from Texas or Florida. It does not reset most properties to market value every year. It anchors each property to a base year value and adjusts that figure annually, so two identical houses on the same street can carry very different assessments — lawfully.

In this section

• Proposition 13 and Proposition 8 explained — the 2%/CPI base year limit and the temporary decline-in-value rule.
• The decline-in-value reduction — why a temporary reduction can move an assessed value well beyond 2%.
• The notice of assessed value — why California does not send one to every owner every year.
• Filing an application for changed assessment — the county board, BOE-305-AH, and what the board can decide.
• Evidence for an assessment appeal — what the board may consider, and the burden-of-proof rules.
• California property tax deadlines — the July 2 filing window, the payment calendar, and the county variable deadline.

Who does what

• The county assessor values property as of the January 1 lien date, applies the base year value rules and exemptions, and does not set tax rates. California has 58 county assessors, each with its own public records and its own local practices.
• Your county’s Assessment Appeals Board — a quasi-judicial body, or a hearing officer, under the board of supervisors — hears an application for changed assessment and determines the value. The application is filed with the clerk of the board, not with the assessor.
• The county tax collector mails the tax bill and collects the tax; the bill arrives in two installments, after the appeals window has already opened.
• The State Board of Equalization (BOE) acts in an oversight capacity over the 58 county assessors and publishes the statewide property tax guidance and calendar. It does not decide your value.

The four figures behind a California tax bill

1. Base year value — the market value of the property as established in 1975, or at the last change in ownership or completed new construction. Everything else is measured from this figure.
2. Factored base year value — the base year value adjusted each year by the lower of the change in the California CPI or 2%. This is the ceiling for the property.
3. Assessed value — the lesser of that factored base year value or the property’s market value on January 1 (a Proposition 8 decline-in-value reduction, which is temporary and reviewed every year).
4. Net taxable value — the assessed value after any exemption or exclusion you qualify for (for example the homeowners’ exemption, which must be claimed). The general tax rate is applied to this figure.

Note what is not in that list: the words “appraised value”. California paperwork uses different vocabulary from Texas, and mixing the two leads people to compare figures that mean different things.

Worked example (illustrative)

Illustrative example with made-up round numbers — not a valuation, not your property, and not a prediction. Real figures depend on your own base year value, your county’s records, and the CPI factor for the year.

1. Inputs: the property was purchased in 2020 for $500,000, which established a base year value of $500,000. For this example we apply the full 2% factor each year (the real factor is the lower of the CPI change or 2%).
2. Step — the factor: six annual 2% adjustments bring the factored base year value for 2026 to roughly $563,000. That is the ceiling, not the assessment.
3. Step — the decline-in-value test: suppose the January 1, 2026 market value is $520,000. Because that is less than the factored base year value, the assessor enrolls the lesser figure: $520,000.
4. Result: the property is temporarily assessed below its Proposition 13 ceiling. The reduction is reviewed every January 1. If the market recovers, the assessed value can return toward the factored base year value (about $574,000 for 2027 in this example) — an increase far larger than 2% in a single year, and still lawful, because the ceiling is the base year value, not last year’s assessment.

What this tells you: in California, a large increase between two assessments is not by itself evidence of an error, and a large gap between your assessment and a neighbor’s is not by itself evidence of unfairness either.

What it does not tell you: whether your base year value is right, whether a change in ownership was correctly recorded, what the CPI factor was for the year, or what your final tax bill will be (rates are set by local agencies and include voter-approved debt).

What this does not cover

County-specific procedures, local filing fees, and the filing deadline your own county sets are not covered on this site. AssessCheck has no data connection to any California county assessor, and there is no California screening tool here yet — see why a year-over-year comparison cannot screen California’s limit.