Hi @pk , thank you for your reply.
by "private retirement fund" I mean pretty much the equivalent of a 401(k) in Brazil. It's a fund to which I've made contributions for several years with a corresponding match by my former employer, and the fund is managed by a company that does only that.
I mentioned "trust" and form 3520 actually because I don't really know whether that's considered a trust or if a trust is something entirely different.
Thank you
