@Linda Weygant thank you for the explanation. I do not have a tax preparer/CPA but I am considering one in Canada who seems knowledgeable in this area due to the number of canadians remaining resident in canada but doing business in the US. They however recommended me to a LA tax attorney who said that profits from the trust are protected from Federal tax under the US/UK Tax treaty but unlikely to be protected from the state tax.
As the sale of the properties are under $100K there will be no applicable state tax in any event, simply the 15% federal tax on the gain. In any event as I had not executed the sales agreement I have proposed to the buyer to move all gains into the trust so that I only have one withholding tax matter to be worried about.
I have calculated the overall tax on the gain in question to be approximately $8000 while property taxes (accumulated losses) for each of the 3 prior years on an alternative building owned by the pension fund came to $3500 per year. It would appear despite the US/UK tax treaty the gain would be wiped out by the losses but it would be important to make a note of it at the time of filing.
He states that the filing requirements would simply require annotating the tax return with a statement and reference to the relevant tax treaty when filing the tax return.
Fortunately filing deadline for foreign entities/persons is June
@TK Lewis that seems like a good idea but bearing in mind that a major company that deals with foreign tax filing could not navigate their way easily through my tax issue I would doubt that Elance CPAs would have the requisite experience or knowledge without also referring me to talk to a Tax attorney.
Thanks for your suggestions though.