Proposition 19 lets many eligible California homeowners transfer the taxable value (factored base year value) of their current primary residence to a replacement primary residence anywhere in California. The base-year transfer rules became operative April 1, 2021.
This is especially relevant in Los Angeles County, where moving even a few miles can mean a big jump in market value, and therefore a big jump in property taxes without Prop 19 relief.
Who qualifies for the Prop 19 base-year value transfer?
You may qualify if, on the date your original home is sold, you are in one of these categories (most commonly age 55+):
- Age 55 or older
- Severely and permanently disabled
- Victim of wildfire or other natural disaster (Governor-proclaimed disaster)
A key requirement is that the original home must be your principal residence and be eligible for the homeowners’ (or disabled veterans’) exemption at the time of sale (or within the timing rules tied to the replacement purchase).
Core rules and timing (what people get wrong most often)
1) Two-year window
To use the transfer, the replacement home must be purchased or newly built within two years of selling the original home (the order can be purchase-first or sell-first, but timing matters).
2) Not handled through escrow
The BOE is clear: you generally file after both transactions are complete and you’re living in the replacement home—it’s not done through escrow.
3) Three transfers per eligible homeowner
For age 55+ (and disabled), Prop 19 allows up to three base-year value transfers per person.
How “equal or lesser value” works (the 100% / 105% / 110% test)
Prop 19 compares the full cash value (generally the sale price reported) of the original home to the replacement home, using an allowed adjustment depending on when you buy:
- 100% of original value if the replacement is purchased/built before the original is sold
- 105% if purchased/built within the first year after the sale
- 110% if purchased/built within the second year after the sale
If the replacement is above that adjusted threshold, you can still get partial relief: the taxable value becomes the transferred factored base year value plus the amount the replacement exceeds the adjusted original value.
Key definitions (plain English)
Full cash value
Usually the sale price (or market value enrolled by the assessor) used for comparison.
Factored base year value (FBYV)
Your original assessed value under Prop 13, increased up to 2% per year over time (what many owners casually call their “tax base”). The BOE refers to this as factored base year value for these transfers.
Homeowners’ Exemption (HOX)
A qualifying owner-occupied principal residence gets a $7,000 reduction in taxable value (which reduces the tax bill). It’s a one-time filing with the county assessor, and LA County provides an online application path.
Examples using 1.25% tax base as an example.
Original home sold: $1,000,000
Factored base year value (FBYV): $325,000
Example A – Replacement home $1,000,000 (equal value)
New taxable value: $325,000
Estimated annual tax at 1.25%: $4,063 (vs. $12,500 without Prop 19)
Example B – Replacement home $1,200,000 (higher value)
Excess value: $200,000
New taxable value: $325,000 + $200,000 = $525,000
Estimated annual tax at 1.25%: $6,563 (vs. $15,000 without Prop 19)
Example C – Replacement home $1,500,000 (higher value)
Excess value: $500,000
New taxable value: $325,000 + $500,000 = $825,000
Estimated annual tax at 1.25%: $10,313 (vs. $18,750 without Prop 19)
How to apply in Los Angeles County
Step 1) Gather your basics
Have on hand:
- Original property address + APN (Assessor Parcel Number)
- Replacement property address + APN
- Sale date/price of original and purchase date/price of replacement
- Your age/qualification documentation (if applicable)
Step 2) File the correct Prop 19 claim with the LA County Assessor
For age 55+, Los Angeles County uses the BOE claim form BOE-19-B (Claim for Transfer of Base Year Value…). LA County posts the form and provides forms access through their site.
Deadline: The BOE summary table indicates these claims are generally due within 3 years of purchasing/completing new construction of the replacement residence.
Step 3) Make sure your replacement home is treated as your principal residence
Prop 19 requires that you own and occupy the replacement home as your primary residence, and you’ll typically want your Homeowners’ Exemption on file where applicable (LA County provides an online “Apply for HOX” workflow).
Step 4) Expect supplemental bills to be part of the process
When ownership changes or construction completes, LA County can issue supplemental property tax bills based on timing within the fiscal year. The LA County Treasurer & Tax Collector explains how those are prorated and when two supplementals can occur.
Special circumstances (LA County + statewide rules)
Severely disabled
LA County notes that a Prop 19 base-year transfer for severely disabled persons generally involves BOE-19-D plus BOE-19-DC (Certificate of Disability).
Wildfire / natural disaster victims
Prop 19 includes a disaster pathway (with separate claim forms such as BOE-19-V) and specific timing/eligibility rules published by the BOE.
Proposition 19 and property taxes for heirs (important change)
Prop 19 limits the ability to pass a low Prop 13 tax base to children/grandchildren. For transfers on/after February 16, 2021, the parent-child exclusion is generally limited to a family home (principal residence) that becomes the child’s principal residence (and family farms), subject to a value limit mechanism.
The BOE explains the value limit concept as: factored base year value + $1,000,000 (with rules for how excess value is added back when market value exceeds the limit).
Where to get LA County-specific help and forms
LA County Assessor – Proposition 19 page (county guidance and summaries).
LA County Assessor – Forms library (Prop 19 forms including parent-child claims).
LA County Assessor – Apply for Homeowners’ Exemption (HOX)
CA Board of Equalization – Prop 19 FAQ hub (statewide rules and examples).
Note: This is general information, not tax or legal advice. Prop 19 rules can be fact-specific, and forms/interpretations can evolve through BOE guidance (including Letters to Assessors).
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