Neillc37

How long have you owned the funds? How long have you been a US person?

Neillc37

To give you some info to work with. A PFIC is a passive foreign investment company. It's a foreign company that derives much of it's income from passive investments (stocks, bonds etc) or has significant holdings in passive investments. This is a trick to capture foreign mutual funds since the funds themselves are small companies. You see terms like ICVC etc.

The US wants to punish you for having these because they were not originally subject to american rules to force income to be realized. In the 80's America was behind the rest of the world in tax deferral.
America has moved on but the PFIC rules remain.
A PFIC can be taxed in three ways.
QEF - Means treat this fund as if it's an American fund. Has to be made when you buy the fund or become a US person otherwise you end up looking like you sold the fund. You can't do it retroactively. You need the fund to have reported lots of stuff to America. Unlikely you can do this.
M2M - Mark to market. You pay income tax on the gains of the fund year on year. You have to elect this and you get the same problems as QEF. You can't do it retroactively.
The default when you don't elect is sec 1291. A mindbogglingly complex system where your gains are spread over the years you owned the fund and you pay the highest marginal tax rate anyone could pay plus interest compounded daily for each day to the present day. I have had to do this stuff because my wife had PFICs.

nun

The OP says that he has an advisor who is filing the PFIC forms. The advisor may have claimed M2M treatment, if so the gain in any value throughout the year will be taxed at the marginal income tax rate. To understand how the PFIC will be taxed we need to know if it's QEF, M2M or the full sec 1291 treatment. I expect it will be M2M.

nun

That's if you feel that SIPPs are not pensions for DTA purposes or you don't claim the treaty exemption.