Does putting my house into a trust trigger a property tax reassessment?

The paperwork is where things go wrong. When the deed is recorded, a Preliminary Change of Ownership Report goes to the county assessor with it, and that form has boxes identifying transfers into a revocable trust by the trustor. If the form is left blank, filled in incorrectly, or omitted, the assessor may open a change in ownership review and issue a supplemental assessment on a transfer that should never have been taxed. It is usually fixable, but it costs letters, time and sometimes a formal claim, and the notice arrives months later when nobody remembers what was signed. An irrevocable trust is a different animal, and a transfer into one can be a change in ownership depending on who holds the beneficial interest, so the analysis here does not carry over to a trust you cannot revoke. And none of this protects the house from Prop 19 when you die: the trust does not exempt the later transfer to your children from reassessment, which is a separate question with a different answer, covered in the question on whether Prop 19 applies when the house is in a living trust. Funding the trust is about avoiding probate and keeping control while you are alive, not about avoiding property tax at your death.