A Prop 19 base year transfer lets a California homeowner who is 55 or older, severely and permanently disabled, or the victim of a wildfire or natural disaster carry the taxable value of the home they sell over to a replacement home anywhere in the state. If you've owned a mid-century house for decades, that can mean keeping your older Proposition 13 value instead of being reassessed at the next home's purchase price.
This guide covers who qualifies, the two-year window, the value test and the claim forms, from State Board of Equalization (BOE) guidance read in November 2026. Passing a home to children is a different part of Prop 19, covered in our guide to Prop 19 inherited home rules.
Who can transfer a base year value under Prop 19
Voters approved Proposition 19 on November 3, 2020, and its base year value transfers have been operative since April 1, 2021. As of November 2026, the rule is in article XIII A, section 2.1(b) of the California Constitution and Revenue and Taxation Code section 69.6, last amended in 2023. You need to fit only one of three groups on the date you sell the original home (section 69.6(b)(3)):
Age 55 or older. The BOE's December 2024 guidance, Letter To Assessors 2024/044, says the claimant must be at least 55 when the original property sells. If only one spouse is 55, that spouse can be the claimant as long as they're an owner of both homes; the age of a spouse who isn't an owner doesn't count.
Severely and permanently disabled. The definition comes from Revenue and Taxation Code section 74.3, and a physician must certify it. There's no age requirement, and the BOE says a parent can't qualify through a disabled child who isn't on title.
Wildfire or natural disaster victim. The original home must have been substantially damaged or destroyed, meaning physical damage of more than 50 percent of the land's or the improvements' full cash value just before the disaster (section 69.6(d)(14)). A natural disaster must be one the Governor proclaimed a state of emergency for. On wildfires, two BOE letters conflict: Letter To Assessors 2021/026 (June 2021) requires a Governor-proclaimed emergency, and the 2024 letter says a wildfire doesn't need one. Neither says it replaces the other.
Both homes must be principal residences. The original must be eligible for the homeowners' or disabled veterans' exemption at the time of sale, within two years of buying the replacement, or just before the disaster damage, and the replacement must be eligible when you file. The BOE says there's no minimum time you must have lived in the original. If you never claimed the homeowners' exemption, the assessor may ask for proof such as voter or vehicle registration.
The two-year window and the order of sale and purchase
Under section 69.6(a) and (b)(5), the replacement must be purchased or newly built within two years before or after the sale of the original home, and at least one of the two transactions has to fall on or after April 1, 2021. The BOE says the two years can't be extended: the period is in the Constitution, and a construction delay or hardship doesn't change it. For a newly built replacement, the completion date is when the local building department inspects and approves it for occupancy.
You can buy first, but the base year value can't move until the original is sold. Until then you pay taxes on the replacement at its full value; the BOE's FAQ says the transfer takes effect at the later date, with no refund for the months in between.
Some transactions don't count:
A home received by gift or inheritance isn't a purchase, so it can't be the replacement.
If you sell the original to your child and the assessor grants the child the parent-child exclusion on it, you can't also transfer its base year value.
How the 100, 105 and 110 percent value test works
The BOE compares the replacement's full cash value on the date of purchase or completion with the original home's full cash value on the date of sale. Under section 69.6(d)(13), the replacement is of "equal or lesser value" if it's no more than:
100 percent of the original's value, if you buy or build the replacement before you sell;
105 percent, if you buy or build it in the first year after the sale;
110 percent, if you buy or build it in the second year after the sale.
If the replacement passes, the original's factored base year value moves over unchanged. Unlike the old Propositions 60 and 90, Prop 19 allows a replacement of any value: under section 69.6(e)(3), the amount above the test is added to the transferred value. In the BOE's own example, an original home with a full cash value of $400,000 and a factored base year value of $100,000 sells, and a replacement is bought in the first year for $600,000. The 105 percent figure is $420,000, so $180,000 is added, and the replacement's taxable value becomes $280,000.
Other points from the 2024 letter:
A house with an accessory dwelling unit counts as one home if the ADU can't be sold separately and you live in one of the units. Each unit of a duplex is generally treated as a separate residence.
If the original is in decline-in-value status, its factored base year value transfers, not the lower temporary value.
If the original has a Mills Act contract, the factored base year value transfers, not the restricted value. Our Mills Act guide explains that contract value.
New construction on the replacement, such as an addition, can get the same relief under section 69.6(e)(7) if it's finished within two years of the sale, its value plus the replacement's value doesn't exceed the original's full cash value at sale, and you notify the assessor in writing within six months of completion.
Anywhere in California, and three transfers for age or disability
The replacement can be in any California county. Under Propositions 60 and 90 a move had to stay in the same county or go to one of 10 counties with an ordinance; that limit is gone. A base year value can't come from a home in another state.
Section 69.6(a) lets an owner who qualifies by age or disability transfer a base year value up to three times, where the old law allowed one. The BOE says earlier transfers under Propositions 60, 90 or 110 don't count against the three. Each spouse has a separate limit, so a couple can potentially use six. Section 69.6(b)(6) says the limit doesn't apply to wildfire or natural disaster victims.
Disaster transfers and the older relief programs
For a wildfire or natural disaster, Prop 19 works from the sale of the damaged property. You sell it in its damaged state and buy or build a replacement within two years of that sale. Letter To Assessors 2021/026 says the disaster itself doesn't have to fall within those two years. A home you rebuild and then sell no longer counts as a disaster original.
The older programs remain. Revenue and Taxation Code section 69 (Proposition 50) allows a same-county transfer within five years of a Governor-proclaimed disaster, and section 69.3 (Proposition 171) allows an intercounty transfer within three years where the receiving county has an ordinance; Santa Clara, San Francisco and Contra Costa were among the 14 such counties the BOE listed as of May 2021. The BOE's disaster relief page says a home rebuilt in a like or similar manner keeps its prior value, and that after a Governor-proclaimed disaster you can rebuild or transfer, but not both.
Filing the claim with the county assessor
Prop 19 relief isn't handled in escrow. The BOE says you file after both transactions close and you're living in the replacement, with the assessor of the county where the replacement is:
BOE-19-B for owners 55 and older;
BOE-19-D, with the physician's certificate BOE-19-DC, for severe and permanent disability;
BOE-19-V for wildfire or natural disaster victims.
Under section 69.6(c), file within three years of buying the replacement or completing its construction. A late claim still gets relief going forward from the lien date of the year you file, but not for earlier years. The sample BOE-19-B the BOE sent assessors in July 2022 asks for an ID showing your date of birth and, if the original is in another county, its latest tax bill and any supplemental bills; our guide to supplemental property tax explains those bills. San Mateo County's assessor accepts BOE-19-B and BOE-19-D through DocuSign or as a PDF. If a claim is denied, the BOE says you can appeal to the county assessment appeals board.
Planning the move from a long-held house
Ask the assessor for your current home's factored base year value; that's the figure that moves.
Buying first sets the test at 100 percent; selling first gives you 105 or 110 percent, with a gap to bridge.
This is general information as of November 2026, not legal or tax advice. The BOE's Prop 19 page says its summary isn't a legal interpretation and encourages talking with an attorney, so confirm your facts with your county assessor and a tax advisor or attorney before you sell.
Frequently asked questions
Can I use a Prop 19 base year transfer if I buy a more expensive home?
Yes. If the replacement is worth more than the 100, 105 or 110 percent test allows, the difference is added to the base year value you transfer.
How many times can I transfer my base year value?
Up to three times if you qualify by age or disability, and transfers under the old Propositions 60, 90 or 110 don't count. Each spouse has a separate limit. The three-time limit doesn't apply to wildfire or natural disaster victims.
Does a wildfire need a Governor's proclamation?
The BOE's letters conflict: Letter To Assessors 2021/026 (June 2021) says yes, and Letter To Assessors 2024/044 (December 2024) says no. A natural disaster other than a wildfire does need one. Ask your county assessor how it reads your case.
Related reading
Selling a Mid-Century Modern Home: What to Fix and What to Leave
Sell a House As Is in California: Original Mid-Century Homes
California Home Sale Requirements for Older Homes: Alarms to Fixtures
Prop 8 Decline in Value: Asking the Assessor for a Lower Value
More guides on this topic: Buying & Selling a Mid-Century Modern Home
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Thinking about selling a long-held mid-century house and buying again in California? Call or text the Boyenga Team at Compass at (408) 373-1660 or (650) 383-8606, or contact the Boyenga Team to plan the timing of the sale and the purchase.
