On Jan 1 of last year my parents put our family cabin into an irrevocable trust with me and my two sisters as trustees. There are no other assets in the trust.

Can the three trustees each take 1/3 of the property tax as an deduction on their individual returns?

What documentation is required?

The taxes for the property (and misc. expenses for it) were paid for from proceeds from another trust, in which the same 3 trustees are the owners of.

“Can the three trustees each take 1/3 of the property tax as an deduction on their individual returns?”------> The Trustees are bound by the Trust document (contract). The trust agreement may specifically outline the requirements and limitations of the trustees.