Historical Proposition 13 Inflation Factors
California Proposition 13 generally limits annual increases in a property's factored base-year value using an official statewide inflation factor, subject to a maximum annual increase of 2%.
Many homeowners assume the increase is always exactly 2%. It is not. In years when the applicable California inflation measure is lower, the official adjustment can also be lower.
This page provides a historical reference of the annual Proposition 13 inflation factors used by the California Property Tax Calculator and explains how those factors affect assessed value over time.
Key point
The 2% figure is a ceiling, not an automatic annual increase.
See How Proposition 13 Factors Compound Over Time
Enter a starting assessed value and acquisition year to see how the official historical factors would increase that value through the latest available assessment year (2026-27).
1975–2026
- Starting value
- $500,000
- Estimated factored base-year value
- $568,915
- Total increase
- +$68,915
- Factors applied (13.8%)
- 7
| Assessment year | Annual increase | Multiplier | Estimated value |
|---|---|---|---|
| 2020-21 | 2.000% | 1.02000 | $510,000 |
| 2021-22 | 1.036% | 1.01036 | $515,284 |
| 2022-23 | 2.000% | 1.02000 | $525,589 |
| 2023-24 | 2.000% | 1.02000 | $536,101 |
| 2024-25 | 2.000% | 1.02000 | $546,823 |
| 2025-26 | 2.000% | 1.02000 | $557,760 |
| 2026-27 | 2.000% | 1.02000 | $568,915 |
Historical Proposition 13 Inflation Factor Table
The table below shows the annual statewide factors used to adjust Proposition 13 factored base-year values. The multiplier is applied to the prior year's value.
Showing 51 of 51 assessment years.
| Allowed increase | Multiplier | |
|---|---|---|
| 2026-27 | 2.000% | 1.02000 |
| 2025-26 | 2.000% | 1.02000 |
| 2024-25 | 2.000% | 1.02000 |
| 2023-24 | 2.000% | 1.02000 |
| 2022-23 | 2.000% | 1.02000 |
| 2021-22 | 1.036% | 1.01036 |
| 2020-21 | 2.000% | 1.02000 |
| 2019-20 | 2.000% | 1.02000 |
| 2018-19 | 2.000% | 1.02000 |
| 2017-18 | 2.000% | 1.02000 |
| 2016-17 | 1.525% | 1.01525 |
| 2015-16 | 1.998% | 1.01998 |
| 2014-15 | 0.454% | 1.00454 |
| 2013-14 | 2.000% | 1.02000 |
| 2012-13 | 2.000% | 1.02000 |
| 2011-12 | 0.753% | 1.00753 |
| 2010-11 | -0.237% | 0.99763 |
| 2009-10 | 2.000% | 1.02000 |
| 2008-09 | 2.000% | 1.02000 |
| 2007-08 | 2.000% | 1.02000 |
| 2006-07 | 2.000% | 1.02000 |
| 2005-06 | 2.000% | 1.02000 |
| 2004-05 | 1.867% | 1.01867 |
| 2003-04 | 2.000% | 1.02000 |
| 2002-03 | 2.000% | 1.02000 |
| 2001-02 | 2.000% | 1.02000 |
| 2000-01 | 2.000% | 1.02000 |
| 1999-2000 | 1.853% | 1.01853 |
| 1998-99 | 2.000% | 1.02000 |
| 1997-98 | 2.000% | 1.02000 |
| 1996-97 | 1.110% | 1.01110 |
| 1995-96 | 1.190% | 1.01190 |
| 1994-95 | 2.000% | 1.02000 |
| 1993-94 | 2.000% | 1.02000 |
| 1992-93 | 2.000% | 1.02000 |
| 1991-92 | 2.000% | 1.02000 |
| 1990-91 | 2.000% | 1.02000 |
| 1989-90 | 2.000% | 1.02000 |
| 1988-89 | 2.000% | 1.02000 |
| 1987-88 | 2.000% | 1.02000 |
| 1986-87 | 2.000% | 1.02000 |
| 1985-86 | 2.000% | 1.02000 |
| 1984-85 | 2.000% | 1.02000 |
| 1983-84 | 1.000% | 1.01000 |
| 1982-83 | 2.000% | 1.02000 |
| 1981-82 | 2.000% | 1.02000 |
| 1980-81 | 2.000% | 1.02000 |
| 1979-80 | 2.000% | 1.02000 |
| 1978-79 | 2.000% | 1.02000 |
| 1977-78 | 2.000% | 1.02000 |
| 1976-77 | 2.000% | 1.02000 |
What Are Proposition 13 Inflation Factors?
When a California property receives a base-year value, that value generally becomes the starting point for future assessments. Each assessment year, the base-year value is adjusted using the statewide Proposition 13 inflation factor.
The annual adjustment is based on the applicable California inflation measure and is limited to a maximum increase of 2%. When the published inflation measure is below 2%, the allowed increase is also below 2%. Applying the annual factors over time produces the property's factored base-year value.
- Base-year value
- Annual statewide inflation factor
- Updated factored base-year value
- Repeat for each assessment year
Why Is the Increase Not Always Exactly 2%?
Proposition 13 does not require assessed values to increase by 2% every year. It generally permits an inflation adjustment of up to 2%. When the official statewide inflation factor is lower, counties use the lower factor, so a property following the normal Proposition 13 path may increase by less than 2% in a particular assessment year.
Over a long ownership period, even small differences can materially affect the estimated factored base-year value. For a $1,000,000 base-year value acquired in 2019 (7 factors applied):
Assuming 2% every year
- Estimated value
- $1,148,686
Using each official historical factor
- Estimated value
- $1,137,829
Assuming a flat 2% overstates the estimate by about $10,856 in this example, because at least one year's official factor was below 2%.
How Inflation Factors Affect California Property Taxes
The inflation factors do not directly determine the property tax bill. They first adjust the property's factored base-year value. The estimated assessed value is then multiplied by the applicable value-based property tax rate. The final tax bill may also contain parcel-specific charges such as Mello-Roos, parcel taxes, special assessments, and supplemental assessments.
- Purchase or base-year value
- Official historical inflation factors
- Estimated factored base-year value
- Applicable ad valorem tax rate
- Estimated property tax
Example: Property Purchased in 2019
This example assumes a $1,000,000 purchase price became the property's base-year value and that no later ownership change, taxable new construction, Proposition 8 reduction, base-year-value transfer, or assessor correction occurred.
| Assessment year | Annual increase | Multiplier | Estimated value |
|---|---|---|---|
| 2020-21 | 2.000% | 1.02000 | $1,020,000 |
| 2021-22 | 1.036% | 1.01036 | $1,030,567 |
| 2022-23 | 2.000% | 1.02000 | $1,051,179 |
| 2023-24 | 2.000% | 1.02000 | $1,072,202 |
| 2024-25 | 2.000% | 1.02000 | $1,093,646 |
| 2025-26 | 2.000% | 1.02000 | $1,115,519 |
| 2026-27 | 2.000% | 1.02000 | $1,137,829 |
- Starting base-year value
- $1,000,000
- Estimated factored base-year value
- $1,137,829
- Estimated increase
- +$137,829
How the Property Tax Calculator Uses These Factors
The California Property Tax Calculator starts with the user-entered purchase price and purchase date. It then applies the applicable historical Proposition 13 factors to estimate the property's current factored base-year value.
The calculator next applies a county-level estimated property tax rate to produce an annual and monthly estimate. Using the official historical factors is more precise than assuming a constant 2% increase for every year.
Use the California Property Tax CalculatorData Sources and Update Policy
The historical factors shown on this page are based on official California property-tax publications and are also used by the California Property Tax Calculator. The dataset is reviewed when a new statewide assessment-year inflation factor is published; the page and calculator are updated together so both use the same annual factor table.
Dataset details
- Source:
- California State Board of Equalization — Letters to Assessors (annual CCPI inflation factors)
- Latest assessment year:
- 2026-27
- Historical coverage:
- 1976-77 to 2026-27 (51 years)
- Last reviewed:
- August 2026
Frequently Asked Questions
Are Proposition 13 inflation factors the same in every county?
Yes. The annual Proposition 13 inflation factor is statewide. County tax rates, Tax Rate Area rates, and parcel-specific assessments can still differ by location.
Is the annual Proposition 13 increase always 2%?
No. The adjustment is capped at 2%, but the official annual factor may be lower.
Does the factor increase a property's market value?
No. It adjusts the property's Proposition 13 factored base-year value. It does not estimate what the property would sell for.
Does every property follow this exact factor history?
Not necessarily. New construction, ownership changes, Proposition 8 reductions, transferred base-year values, exemptions, escape assessments, disaster relief, and assessor corrections can cause the official enrolled value to differ.
What is the difference between an allowed increase and a multiplier?
The allowed increase is the percentage adjustment. The multiplier is the decimal factor applied to the prior value. For example, a 2% increase corresponds to a multiplier of 1.02000.
Why does the calculator ask for the purchase date?
The purchase date helps determine when the new base-year value began and which annual inflation factors apply.
Can an assessed value increase by more than 2%?
Yes, in some situations. For example, a property with a temporary Proposition 8 reduction can increase by more than 2% as market value recovers toward the normal Proposition 13 factored base-year value.
Are these factors enough to calculate the official tax bill?
No. They help estimate the factored base-year value. The official tax bill also depends on the enrolled taxable value, local ad valorem rates, direct assessments, exemptions, and parcel-specific charges.
Related California Property Tax Resources
This page is provided for educational purposes and summarizes publicly available California property-tax information. It does not determine a property's official assessed value or tax bill. County assessors and tax collectors determine official values and charges, and individual properties may be affected by reassessment events, Proposition 8 reductions, new construction, exemptions, direct assessments, or other circumstances.