How Prop 19's parent-child exclusion works, in brief
Proposition 19 allows a child to inherit a parent's primary residence without a full property tax reassessment, provided the child makes the home their own primary residence within one year of the transfer and files the required exemption paperwork. But the exclusion isn't unlimited — it's capped at the parent's existing factored base year value plus an inflation-adjusted allowance (currently just above $1 million, adjusted periodically). Any value above that combined cap gets added to the tax base, triggering a partial reassessment on the excess.
Where an ADU changes the math
An ADU adds real, tangible value to a property's fair market value at the time of transfer — potentially enough to push the total value over Prop 19's exclusion cap, even if the home without the ADU would have stayed comfortably under it. In that scenario, the ADU's value doesn't get a separate, special exemption — it simply becomes part of the fair market value figure that Prop 19's cap is measured against.
Illustrative example only — not a specific calculation
The figures above are illustrative only — the actual exclusion allowance adjusts periodically, and your specific numbers depend on your parent's actual base year value and the property's actual appraised value at transfer. This is a distinct question from what happens when you personally build a new ADU, which triggers its own separate, smaller reassessment tied only to the new construction itself.
Practical steps worth taking
- Get an accurate appraisal at transfer that reflects the property's actual condition, including the ADU, rather than relying on a rough estimate.
- File the required exclusion claim on time — generally the Claim for Reassessment Exclusion for Transfer Between Parent and Child (BOE-19-P), within the applicable filing deadline.
- Confirm the current exclusion allowance with your county assessor, since the inflation-adjusted figure changes periodically.
- Talk to a property tax professional before the transfer if the property's value (including the ADU) is anywhere near the cap — there may be planning considerations worth discussing in advance.
This is general information, not tax or legal advice
Prop 19's rules involve specific filing deadlines, valuation methods, and eligibility requirements that depend on your family's exact situation. This page describes the general framework, not a determination for your specific transfer. A property tax professional or estate attorney should review your actual numbers and timeline.
Frequently asked questions
It doesn't affect your eligibility for the exclusion itself, but it does add to the property's fair market value, which is measured against Prop 19's exclusion cap. A higher value from the ADU can mean more of the property gets partially reassessed if the total exceeds the cap.
No — building an ADU yourself triggers a separate, generally smaller reassessment tied only to the new construction's value. Inheriting a property under Prop 19 involves a different question: whether the property's total value at transfer exceeds the parent-child exclusion cap.
Generally yes — you need to establish the property as your own primary residence within one year of the transfer and file the required homeowners' exemption to qualify.