The investing mistakes that cost retirees the most.
Three asset categories carry tax consequences disproportionate to how innocuous they look: foreign mutual funds and ETFs, foreign retirement accounts, and rental property abroad. Each has its own form, its own penalties, and its own way of turning a manageable tax bill into a problem.
The PFIC trap is the worst of the three by a wide margin. If you're going to read one section, read that one.
Updated · Published
Educational only. Foreign-asset tax rules are unusually punitive and unusually situational — before you buy a foreign fund, open a foreign retirement account, or buy a rental property abroad, talk to an expat CPA.
The fund that could
cost you 50%+ in tax.
Foreign mutual funds and foreign-domiciled ETFs trigger PFIC rules — Passive Foreign Investment Company. Long-term capital gains get converted to ordinary income, an interest charge is added on top, and annual reporting (Form 8621) runs 22+ hours per fund.
The penalty for not filing Form 8621 is $10,000 per fund per year. Effective tax rates above 50% on gains are common.
A 2-letter rule that saves a 5-figure mistake.
Look at the first 2 letters of the fund's ISIN code (printed on every brokerage statement).
Practical rule: keep your investment accounts at a US brokerage and buy US-registered funds — even ones that invest entirely in foreign stocks. They're not PFICs. Foreign brokerages and foreign-domiciled funds are. Not all US brokerages follow you abroad — see which ones do.
PFIC estimate assumes a 5-year hold. Interest charge varies by holding period and IRS underpayment rate.
And the filing cost adds up.
Form 8621 runs $200 for the first PFIC and $150 for each additional one at TFX — on top of the standard $450 federal return. Two foreign funds in your portfolio adds $350 to your preparation cost every year, before any actual tax. The cheaper move is almost always to not own them.
Don't open the local
pension yet.
If you open a local pension or retirement savings account in your new country — common in Australia (super), the UK (SIPP), France (PER) — US tax treatment depends heavily on the country's treaty.
An unrecognized foreign pension can trigger annual Form 3520 / 3520-A, and the growth inside may be taxable to the US each year, even if you never withdraw. Penalties for missed Form 3520 filings start at $10,000 or 5% of the asset value, whichever is greater.
This is the rare case where pre-move advice is genuinely required.
The US-UK treaty recognizes most UK pensions. The US-Australia treaty is less clear on superannuation. France and Germany are case-by-case. A one-hour conversation with an expat CPA before you open any local retirement account can prevent years of compounding paperwork. After the account exists, your options narrow considerably.
Rent out property abroad?
The IRS wants to know.
If you rent out property in your new country — even a guest cottage on Airbnb — that income is reportable on your US return. You'll generally owe US tax on net rental income (after expenses), and a foreign tax credit typically offsets what you paid locally.
You're usually not paying twice — but you do need to report it. Foreign rental adds Schedule E to your return and, if rental income is held in a foreign bank account, may push you over the FBAR threshold or trigger FATCA reporting on Form 8938.
Depreciation works differently abroad.
US tax rules require foreign residential rental property to be depreciated over 30 years (vs. 27.5 for US property). Small difference, but it matters when computing your annual deduction. Your expat CPA will handle this — just flag it so it doesn't get missed.
Already own a foreign fund or considering one?
This is the area where specialist advice pays for itself fastest. TFX handles PFIC reporting routinely — $200 for the first fund, $150 for each additional, on top of the standard $450 federal return. Better: a 30-minute conversation before you buy.