How much house can you buy and still keep your tax base?
If you’re 55 or older, Proposition 19 lets you carry your low assessed value to a replacement home anywhere in California. But there’s a ceiling — and it moves depending on whether you buy before you sell, in the first year after, or in the second. This works out your number.
Your numbers
Not what the home is worth — what the county taxes you on. It’s the “net assessed value” line on your property tax bill, or look it up on your county assessor’s site.
Its full cash value. The assessor generally presumes this is the sale price, but is not strictly bound by it.
The two-year window runs in both directions, but the allowance only exists if you sell first. Buy first and the threshold drops to 100%.
The 1% Prop 13 base rate plus voter-approved bonds and direct assessments. Most parcels in Santa Clara and Santa Cruz counties land between 1.1% and 1.3%. Check a recent tax bill for yours.
At the price you entered
| Allowance threshold | $0 |
| Replacement price | $0 |
| Amount over the threshold | $0 |
| Your transferred base | $0 |
| New taxable value | $0 |
What it saves you
| Annual tax with the transfer | $0 |
| Annual tax without it (fresh assessment) | $0 |
| Saved every year | $0 |
Prop 13 caps increases at 2% a year on both figures, so the gap widens over time rather than closing.
Timing changes the answer
Same two houses, three different sequences. This is the part people find out about too late.
| When you buy | Threshold | Added to your base | New taxable value | Annual tax |
|---|
Buying before you sell also means paying tax on the replacement’s full market value for the gap between the two closings, with no refund for that period.
The fine print, stated plainly: this is an educational estimate, not tax or legal advice. It applies the “equal or lesser value” test in California Property Tax Rule 462.540(c)(2) and the base year value formula in Rule 462.540(b). It assumes both homes are your primary residence, that you or your spouse are 55 or older when the original sells, that you have not already used the transfer three times, and that both properties are in California. It does not handle new construction, partial interests, mixed-use parcels, disaster transfers, or the severely-disabled provisions. Your county assessor makes the actual determination, and full cash value is the assessor’s finding — not automatically your contract price. I’m a broker, not a CPA or an attorney.
The rule in one paragraph
Proposition 19 lets a homeowner 55 or older transfer the factored base year value of their primary residence to a replacement primary residence anywhere in California, up to three times. If the replacement is worth the same or less than the original, your assessed value simply moves with you, unchanged.
If the replacement is worth more, you don’t lose the transfer — and you don’t get the full difference added, either. Only the amount above the threshold gets added to your old base. The threshold is 100% of the original’s full cash value if you buy before you sell, 105% if you buy within the first year after the sale, and 110% in the second year.
Cal. Property Tax Rule 462.540(c)(2); Rev. & Tax. Code §69.6.
Worth knowing
- The age test is met at the moment the original home sells. Being 54 at the sale and 55 at the purchase does not qualify.
- Only the spouse who is 55+ can be the claimant, and that spouse must be an owner of both homes.
- Prior use of Props 60, 90 or 110 does not burn any of your three transfers.
- Disaster-related transfers don’t count against the three-time limit.
- The two-year window is in the California Constitution. There is no hardship exception.
- File BOE-19-B with the assessor in the county of your new home, within three years of the purchase. This is not done through escrow — you file it yourself after you’ve closed and moved in.
- File late and relief starts from the lien date of the year you file. No retroactive refunds.
- Sell first and the original’s value gets inflation factoring between the two closings, which nudges your threshold up. Buy first and it doesn’t.
The ones I actually get asked
Do I lose the whole transfer if I buy something more expensive?
No. That’s the most common misunderstanding. Going over the threshold doesn’t disqualify you — it just adds the overage to your transferred base. You keep the benefit on everything underneath.
Is the difference added, or just the amount over the threshold?
Only the amount over the threshold, as long as you sold first. Sell for $2.6M and buy for $3.0M within a year: the 105% threshold is $2,730,000, so $270,000 gets added — not $400,000. Buy before you sell and the threshold is 100%, so the full $400,000 does get added.
What if I buy before I sell?
Still allowed — the two-year window runs both directions. But you lose the allowance, so the threshold is 100% of the original’s value. And because the transfer takes effect on the later of the two events, you pay property tax on the replacement’s full market value in the meantime, with no refund for that period.
Does this work between counties?
Yes, all 58 of them. That was the biggest change from the old Props 60 and 90, which only worked in counties that opted in. Both properties have to be in California, though — you can’t bring a base year value in from another state.
Can my spouse and I each use it three times?
Potentially, yes — the three-transfer limit attaches to the claimant. In practice that’s a question for your county assessor given how you hold title.
What counts as “full cash value”?
The assessor’s determination of market value. It’s presumed to be the purchase price, but the assessor isn’t bound by your contract — an unusual sale can be looked at differently.
Does this have anything to do with capital gains?
No. Prop 19 is property tax only. Capital gains is a completely separate calculation — basis, improvements, the §121 exclusion, federal and California rates. The net proceeds calculator handles that side.
What about inheriting a home — is that the same rule?
Different provision entirely, with much tighter conditions. A child has to move in within one year and the exclusion is capped. That’s covered here, and the sell-now-or-inherit trade-off is here.
Want me to sanity-check your scenario?
Send me your numbers and I’ll run them by hand, flag anything the calculator can’t see, and tell you plainly if the sequence you’re planning costs you money. No obligation, and no call unless you ask for one.
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The calculator shows the ceiling. Sequencing decides whether you hit it.
Which house goes first, how the contingencies are written, and how long the gap runs between closings — that’s where the real money is on a Prop 19 move.
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