Does Prop 19 apply if the house is in a living trust?

Keep this separate from the opposite situation. Putting your own house into your own revocable trust is a different question, and the answer there is no; that transfer is not a change in ownership and does not trigger reassessment. See the question on whether funding a trust causes a reassessment, because the two answers do not contradict each other. The distinction is control. Moving title into a trust you can revoke changes nothing economically, while a death that fixes the property in the hands of the next generation changes everything. Practically, the trustee is the one who has to act, since the trustee holds title and signs the deed that distributes the house. The exclusion claim goes to the county assessor, the child who is going to live in the house has a separate and much shorter window to claim the homeowners' exemption, and neither filing happens on its own; the question on where to file and what the deadlines are covers both. One more thing is worth checking while a parent is still alive. The exclusion only reaches children. If the trust leaves the house to a niece, a nephew, or a friend, there is no parent-child exclusion at all and the property is reassessed to full market value, and a trust written twenty years ago may still send the house somewhere the family no longer intends.