Proposition 19 lets a California homeowner aged 55 or older move their existing property-tax base to a replacement primary residence anywhere in the state, up to three times. The rule that decides what that costs you is the value test in Property Tax Rule 462.540(c)(2), and it gets misread in two different directions.
Misreading one: “it has to be equal or lesser value”
It does not. There is a threshold, and buying above it is allowed — it simply adds something to your new base. The threshold depends on sequence and timing:
| When you buy the replacement | Threshold |
|---|---|
| Before the original sells | 100% |
| Within one year after the sale | 105% |
| In the second year after the sale | 110% |
Misreading two: “it can exceed the original by 105%”
Read literally, that sentence means the replacement can be worth 205% of the original. It is wrong, and it is an easy sentence to write by accident — it was on two pages of this site until a review caught it. I am flagging it here precisely because if I wrote it twice, it is out there elsewhere.
The correct phrasing: the replacement may be worth up to 105% of the original. Not exceed it by 105%.
And then the arithmetic people actually get wrong
Even with the threshold right, the common assumption is that buying above it means the whole difference is added to your tax base. It is not. Only the amount above the threshold is.
New base year value = your factored base year value + (replacement’s full cash value − the threshold). Only the excess. Never the full difference.
Two worked examples, both published by the Board of Equalization, both reproduced exactly by the calculator on this site:
BOE FAQ #6. Factored base year value $100,000. The original sells for $400,000. The replacement is bought in the first year after, for $600,000. The threshold is 105% of $400,000, or $420,000. The excess is $600,000 − $420,000 = $180,000. New base year value: $100,000 + $180,000 = $280,000. Not $600,000, and not $300,000.
Rule 462.540, Example 8. Factored base year value $300,000. Original sells for $550,000. Replacement costs $600,000. Threshold $577,500. Excess $22,500. New base year value: $322,500.
In that second example the buyer went $50,000 above the sale price of their old home, and it moved their assessed value by $22,500. At a typical rate near 1.15%, that is roughly $259 a year. People routinely walk away from a better house over a misunderstanding of that size.
The rest of the test, briefly
- Two years, either direction. Buy first and sell within two years, or sell first and buy within two. This sits in the Constitution, and there is no hardship exception.
- Age is tested when the original sells, not when you buy. Only the spouse who is 55 or older can claim it, and that spouse must own both properties.
- Three times, across all 58 counties. Disaster-related transfers do not count against the three, and prior use of Propositions 60, 90 or 110 does not burn any of them.
- File BOE-19-B in the county where the replacement is, within three years. This does not happen through escrow. Nobody does it for you.
One caution on sources: the Board’s Publication 801 states this loosely enough to mislead. Rule 462.540(c)(2) is the operative text.
Sequence matters more here than almost anything else, and buying before selling costs you twice over — that has a post of its own.