Editorial note: Gold California is not a tax advisor, a licensed attorney, or a county assessor. This page is a plain-English worked example of the Proposition 19 base year value math for California homeowners age 55 and older.
Every rule, threshold, and code section is cited to the California Board of Equalization or the Revenue and Taxation Code. The dollar figures in the worked examples are illustrative only and do not reflect any specific home, sale, or purchase. Consult a licensed California CPA, attorney, or your county assessor for your specific situation.
Last updated: August 15, 2026 · By Gold California Editorial
Quick answer: If a Prop 19 replacement home is worth equal to or less than the original, the factored base year value carries over unchanged. If the replacement is worth more, the excess above the timing-adjusted original value is added to the transferred base. The 1 percent Prop 13 rate then applies to that new base.
Short on time? The essentials
- The base year value transfer for California homeowners age 55 and older is set out in Revenue and Taxation Code section 69.6, which implements Proposition 19.
- The base transfer provisions became operative on April 1, 2021, and apply statewide since that date.
- The equal-or-lesser-value test uses three timing thresholds: 100 percent of the original full cash value if the replacement was bought before the sale, 105 percent if bought in the first year after, and 110 percent if bought in the second year after.
- If the replacement is worth equal to or less than that timing-adjusted figure, the factored base year value carries over unchanged.
- If the replacement is worth more, the difference between the replacement and the timing-adjusted original is added to the transferred base.
- The claim is allowed up to three times over the lifetime of an age-55-or-older claimant.
- The 2 year window between the sale and the purchase is a hard rule in section 69.6; late transactions do not qualify.
- The 1,000,000 dollar cap that many readers have heard about applies to the Prop 19 parent-child exclusion in section 63.2, not to the 55-and-older base year value transfer covered on this page.
- All dollar figures in the worked examples below are illustrative; confirm your own numbers with your county assessor and a licensed California CPA.
This page is for California homeowners age 55 and older weighing a Prop 19 base year value transfer, and for adult children, surviving spouses, or executors who need to run the math before signing anything. Below we show three fully worked examples using illustrative dollar amounts. A 10 year property tax comparison follows to help see the size of the tax benefit under Prop 19 versus a market reassessment at the replacement's purchase price.
All dollar figures in the examples are labeled ILLUSTRATIVE. The rules, thresholds, and code sections are drawn from the California Board of Equalization and Revenue and Taxation Code section 69.6, cited inline and in the Sources section at the end. This page is not tax advice. Confirm your specific numbers with your county assessor and a licensed California CPA.
What "worked math" means for a Prop 19 base transfer
A base year value transfer moves the assessed value of a sold principal residence over to a replacement principal residence. The property tax on the new home is then calculated on the older, lower base instead of the new purchase price. The math determines the new base after two variables interact: the price of the replacement versus the price of the original, and the timing between the sale and the purchase.
Under Proposition 13, a California property's local ad valorem tax rate is capped at 1 percent of assessed value. The assessed value grows by 2 percent or California inflation each year, whichever is lower (source: California Board of Equalization, Property Tax overview). Selling and rebuying normally resets that base to the new purchase price. Prop 19 lets qualifying homeowners keep the old base under specific rules.
The statutory authority for the age-55-or-older transfer is Revenue and Taxation Code section 69.6, which implements Article XIII A, section 2.1 of the California Constitution (source: California Legislative Information, RTC section 69.6). The provisions became operative on April 1, 2021.
The three inputs and the timing factor
Before doing any math, gather three numbers and one date. Everything else follows.
- Full cash value of the original home at the time of sale. This is the price the original home actually sells for on the open market, or the assessor's market-value estimate at that date.
- Factored base year value of the original home at the time of sale. This is the assessed value line on the last property tax bill for the original home, grown at the annual Prop 13 cap.
- Full cash value of the replacement home. This is the price paid for the replacement, or the completed cost of newly constructed housing on land already owned.
- Timing between the sale and the purchase. Whether the replacement was bought before the sale, in the first year after the sale, or in the second year after the sale sets the equal-or-lesser-value threshold.
The timing factor comes from the definition of "equal or lesser value" in RTC section 69.6. The BOE summarizes the three settings on its Prop 19 page (source: California Board of Equalization, Proposition 19).
| When the replacement was purchased or newly constructed | Multiplier applied to original full cash value | Meaning |
|---|---|---|
| Before the sale of the original home | 100 percent | Replacement must be worth no more than the original's full cash value. |
| Within the first year after the sale of the original home | 105 percent | Replacement can be worth up to 5 percent more without any adjustment. |
| Within the second year after the sale of the original home | 110 percent | Replacement can be worth up to 10 percent more without any adjustment. |
Source: California Board of Equalization, Proposition 19 base year value transfer table for persons at least age 55 or disabled, boe.ca.gov/prop19. Definition of "equal or lesser value" is set out in Revenue and Taxation Code section 69.6, subdivision (a) definitions paragraph 13. Checked August 2026.
With these four items in hand, the math falls into one of two paths. Either the replacement is worth equal to or less than the timing-adjusted original, in which case the factored base year value carries over unchanged. Or the replacement is worth more, in which case the difference between the replacement and the timing-adjusted original is added to the transferred base.
The rest of this page walks the three cases with illustrative numbers, then converts each into a year-1 property tax at the 1 percent Prop 13 base rate before any voter-approved local add-ons.
Case A: Replacement equal to or less than the timing-adjusted original
The simplest case. The replacement's full cash value is equal to or less than the timing-adjusted original figure. The factored base year value carries over to the replacement without any change.
Case A also covers the common downsize scenario. A homeowner sells a family home worth 1,200,000 dollars, buys a smaller replacement for 800,000 dollars within the same year. The 800,000 dollar replacement is well under the timing-adjusted 1,260,000 dollar figure. The factored base year value simply moves over unchanged. Downsizes almost always land in Case A.
Case B: Replacement modestly greater than the original
The replacement is worth more than the timing-adjusted original, but the excess is a modest amount rather than a large jump. The excess is added dollar for dollar to the transferred base year value.
The BOE gives a similar worked example on its Prop 19 FAQ, using an original home at 400,000 dollars with a 100,000 dollar factored base and a replacement at 600,000 dollars bought within the first year. The BOE result is a new base of 280,000 dollars on the replacement (source: California Board of Equalization, Proposition 19 FAQs, worked example).
Case C: Replacement substantially greater than the original
The replacement is worth substantially more than the timing-adjusted original, either because the family upgraded, moved to a higher-priced county, or bought a home with an accessory dwelling unit. The formula is the same as Case B; only the size of the excess is larger.
A pattern emerges when Case B and Case C are compared side by side. Both produce the same illustrative year-1 saving of 7,650 dollars, even though the replacement in Case C costs 600,000 dollars more. That is because once the replacement is greater than the timing-adjusted original, any additional replacement dollars add one-for-one to both the transferred base and to the market baseline. The tax on that extra amount is the same either way.
| Item | Case A | Case B | Case C |
|---|---|---|---|
| Original full cash value at sale | $900,000 | $900,000 | $900,000 |
| Original factored base year value | $180,000 | $180,000 | $180,000 |
| Timing factor | 105% | 105% | 105% |
| Timing-adjusted original full cash value | $945,000 | $945,000 | $945,000 |
| Replacement full cash value | $900,000 | $1,400,000 | $2,000,000 |
| Excess added to base | $0 | $455,000 | $1,055,000 |
| New base year value on replacement | $180,000 | $635,000 | $1,235,000 |
| Year-1 property tax at 1% base rate | $1,800 | $6,350 | $12,350 |
| Market reassessment tax at 1% base rate | $9,000 | $14,000 | $20,000 |
| Illustrative year-1 saving | $7,200 | $7,650 | $7,650 |
All figures illustrative. Formula source: California Revenue and Taxation Code section 69.6, subdivisions (a) and (g); California Board of Equalization Proposition 19 FAQs at boe.ca.gov/prop19. The 1 percent local ad valorem rate cap is set out in Article XIII A of the California Constitution (Proposition 13). Voter-approved local bond add-ons are excluded from these numbers. Checked August 2026.
Illustrative 10 year property tax savings across the three cases
The property tax saving from a Prop 19 base transfer compounds over the years the homeowner keeps the replacement. Both the transferred base and the alternative market baseline grow at the Prop 13 annual cap of 2 percent or California inflation, whichever is lower.
The chart below shows an illustrative annual property tax saving for each of the three cases across a 10 year hold, assuming both the transferred base and the market baseline grow at the 2 percent cap each year. The 1 percent base rate is applied; voter-approved local add-ons are excluded because they vary by taxing jurisdiction.
Two takeaways from the chart. First, the annual saving in Case B and Case C converges at 7,650 dollars in year 1 and grows at the 2 percent cap thereafter, because the math above the timing-adjusted threshold behaves the same in both. Second, Case A carries a slightly lower annual saving of 7,200 dollars in year 1, because the replacement in Case A costs less than the timing-adjusted threshold, so a small slice of the potential benefit is not used.
The cumulative 10 year saving in the chart's illustrative setup is approximately 78,800 dollars for Case A and 83,800 dollars for Case B and Case C. These are illustrative figures at a 1 percent base rate before local add-ons. Your county's actual voter-approved bonds, school parcel taxes, and other add-ons will change the totals in either direction. Ask your county assessor for the current combined rate for the tax rate area of the replacement home.
The 1,000,000 dollar cap belongs to a different Prop 19 rule
Many California homeowners have read about a 1,000,000 dollar Prop 19 cap in the news. That cap applies to the parent-child exclusion, which is a separate provision inside Proposition 19 and lives in Revenue and Taxation Code section 63.2 (source: California Board of Equalization, Proposition 19). It does not apply to the age 55 and older base year value transfer in section 69.6.
The parent-child exclusion is the rule that governs what happens to the property tax base when a parent transfers a California home to a child by gift or inheritance. Under Prop 19, the exclusion applies only if the child then makes the home the child's own principal residence. The value cap is the parent's factored base year value plus 1,000,000 dollars, indexed.
The BOE lists the operative amounts as follows. From February 16, 2021 through February 15, 2023, the cap is 1,000,000 dollars. From February 16, 2023 through February 15, 2025, it is 1,022,600 dollars. From February 16, 2025 through February 15, 2027, it is 1,044,586 dollars (source: California Board of Equalization, Proposition 19 intergenerational transfer exclusion adjustments).
The 55-and-older base year value transfer on this page has no 1,000,000 dollar cap. The math above the timing-adjusted threshold is a straight dollar-for-dollar add of the excess to the transferred base. Confusing the two provisions is the single most common Prop 19 misunderstanding we see.
How to run the math yourself with your county assessor
The steps below produce the same math shown in the worked examples, using the numbers on your own property tax bill and your own sale and purchase dates.
- Pull the last property tax bill for the original home. The line labeled "Assessed value" or "Total taxable value" is the factored base year value that would transfer.
- Get the full cash value at time of sale. The sale price on the closing statement is the standard proxy; the county assessor may substitute an appraised value if a sale is not arm's length.
- Determine the timing factor. Was the replacement bought before the sale of the original, in the first year after, or in the second year after? Apply 100 percent, 105 percent, or 110 percent.
- Compute the timing-adjusted original full cash value. Multiply the original's full cash value at sale by the timing factor.
- Compare to the replacement's full cash value. If less than or equal, the factored base year value carries over. If greater, the excess adds to the base.
- Compute the new base year value on the replacement. Original factored base year value plus any excess equals the new base on the replacement.
- Multiply by the 1 percent base rate for a year-1 base tax estimate. Then add the voter-approved local bond and parcel-tax add-ons from your county assessor's rate sheet for the replacement's tax rate area.
- Confirm the numbers with the county assessor of the replacement home. Every assessor publishes tax rate area sheets and, on request, will walk through a base year value transfer estimate.
When the math advantage is small or negative
Not every situation produces a large Prop 19 benefit. Four common patterns leave the math advantage small, or dominated by unrelated costs.
- The original home was purchased recently. If the original was bought only a few years before the sale, the factored base year value is close to the current full cash value. The transferred base already looks a lot like a market baseline, so the year-over-year saving is modest.
- The replacement will be sold quickly. Selling costs, moving costs, and a second round of closing costs can eat several years of property tax savings. A hold of only three or four years may not clear the transaction cost.
- The replacement is in a much higher-cost county. A large upward move in home price adds one-for-one to the transferred base above the timing-adjusted threshold. The savings still exist, but they are smaller relative to total housing outlay.
- One of the three lifetime uses is being spent on a small benefit. The 55-and-older claimant is allowed up to three transfers over a lifetime. Using one for a modest saving may not be the best strategy if a larger move is likely in the coming years.
None of these patterns disqualify a transfer. They are reasons to run the numbers carefully and to think about the full picture before filing. Talk with a licensed California CPA about your household's specific facts.
Prop 19 worked-math questions, answered
Does the timing factor of 100, 105, or 110 percent apply to the base year value or to the full cash value?
It applies to the original home's full cash value at sale, not to the factored base year value. The timing-adjusted figure serves two purposes only. It tests whether the replacement is "equal or lesser value". If the replacement exceeds it, it defines the excess added to the base (source: RTC section 69.6, definition of equal or lesser value).
Is the 1 percent Prop 13 rate the only property tax I will owe?
No. The 1 percent is the Proposition 13 base rate cap on ad valorem tax. Every California property also pays voter-approved local add-ons: school bonds, community college bonds, water district assessments, and parcel taxes. These add-ons vary by tax rate area. Ask the county assessor of the replacement home for the current combined rate before finalizing any budget (source: California Board of Equalization, Property Tax overview).
What if I bought the replacement before I sold the original?
Section 69.6 allows that sequence. The base year value does not transfer until the original is sold, but the sale must occur within 2 years of the purchase of the replacement. The timing factor at 100 percent applies in that case, meaning the replacement must be worth no more than the original's full cash value at the later sale to avoid an adjustment (source: California Board of Equalization, Proposition 19).
Do inflation adjustments on the factored base year value apply between sale and replacement?
Yes. If the replacement is purchased or newly constructed after the sale of the original, section 69.6 adds Prop 13 inflation factor adjustments to the "taxable value of the original property". Those adjustments cover the period between the sale and the transfer date (source: RTC section 69.6, subdivision (g)(4)). In practice, that adjustment is small over a two year window at the 2 percent cap.
Does the excess added to the base grow at 2 percent a year like the original base?
Yes. Once the new base year value is set on the replacement, the full amount, including the excess added, grows at the Prop 13 annual cap of 2 percent or California inflation, whichever is lower. There is no separate track for the transferred portion versus the added excess.
What happens if my two homes are in different counties?
The Prop 19 base year value transfer is statewide since April 1, 2021. Any California county to any California county is allowed under section 69.6 (source: California Board of Equalization, Proposition 19). The county-by-county acceptance rules that applied under prior Propositions 60 and 90 no longer apply to transfers with a qualifying sale on or after that date.
Do these worked examples reflect what I will actually owe on a specific home?
No. The dollar amounts are illustrative and are meant to show how the formula works. Your actual base year value depends on four inputs.
- The assessor's determination of your original home's full cash value at sale.
- Your factored base year value on the last property tax bill.
- The timing of your purchase.
- The replacement's confirmed full cash value.
Ask your county assessor for a written base year value transfer estimate before making any final financial decision.
How many times can I use this transfer over my lifetime?
Three times, as a claimant who is over 55 years of age or severely and permanently disabled. Prior use of the older Propositions 60, 90, or 110 does not count against the three Prop 19 uses (source: California Board of Equalization, Proposition 19 FAQs). A spouse pair is treated as one claimant unit.
Sources
- California Board of Equalization. Proposition 19: The Home Protection for Seniors, Severely Disabled, Families, and Victims of Wildfire or Natural Disasters Act. Checked August 2026.
- California Legislative Information. Revenue and Taxation Code section 69.6. Checked August 2026.
- California Board of Equalization. Letter to Assessors No. 2020/061: Proposition 19, December 2020. Checked August 2026.
- California Board of Equalization. Letter to Assessors No. 2021/019: Proposition 19 Base Year Value Transfer Guidance Questions and Answers, 2021. Checked August 2026.
- California Board of Equalization. Letter to Assessors No. 2022/009: Implementation of Proposition 19, Base Year Value Transfers, 2022. Checked August 2026.
- California Board of Equalization. Letter to Assessors No. 2024/044: Proposition 19 Base Year Value Transfer Frequently Asked Questions and Answers, 2024. Checked August 2026.
- California Board of Equalization. California Property Tax overview. Checked August 2026.
- California Legislative Information. Assembly Constitutional Amendment No. 11 (Proposition 19 enabling constitutional amendment). Checked August 2026.
