The 7 Most Expensive US Expat Tax Mistakes

After enough conversations with Americans abroad, the same handful of mistakes appears again and again. Here they are, ranked roughly by how much they cost.

1. Skipping the FBAR

The champion. People diligently file their 1040 and never learn the FBAR exists — because it doesn’t attach to the return. At ~$10,000 per non-willful violation, nothing else on this list competes. If your foreign accounts combined ever exceeded $10,000, it applies to you.

2. Buying Foreign Mutual Funds and ETFs

To the IRS, most non-US pooled investments — mutual funds, many ETFs, some insurance-wrapped products — are PFICs (Passive Foreign Investment Companies). The tax treatment is punitive and the reporting (Form 8621) is notorious. Even modest holdings can generate outsized tax and preparation costs. The standard fix: hold US-domiciled investments where possible, and get advice before buying anything pooled abroad.

3. Quiet Disclosure

Discovering you’re years behind and just… quietly filing them all, hoping nobody notices. It surrenders the penalty protection of the Streamlined Procedures while creating exactly the paper trail examiners look for. If you’re behind, choose an official route — never the quiet one.

4. Breaking the FEIE Day Count

Physical Presence means 330 full days abroad in the window. Travel days to the US don’t count as foreign days; neither do hours over international waters. Expats lose five-figure exclusions over one badly timed trip home. Count days before booking flights, not after.

5. Ignoring State Residency

You moved to Lisbon; California still thinks you live in Sacramento. Sticky states keep claiming residents who didn’t formally cut ties — driver’s license, voter registration, property, even a storage unit can matter. An hour of exit planning saves years of state returns.

6. Forgetting Self-Employment Tax

The FEIE wipes out income tax, not the 15.3% SE tax. Freelancers who don’t claim a totalization exemption (with a certificate of coverage) or budget for the bill get an ugly April surprise.

7. Missing the Refunds You’re Owed

The cheerful one: many expats overpay. Families who claim the FEIE reflexively can forfeit the refundable Child Tax Credit — free money for filers using the Foreign Tax Credit instead. Others never claim treaty benefits on pensions. Filing correctly isn’t only about avoiding penalties; it’s about not donating to the Treasury.

Disclaimer: This article is general information, not tax, legal, or financial advice. Confirm current rules with official sources or a qualified professional. eTaxNexus is a digital brand of Mega Commercial Enterprises Limited, registered in Ireland, Company Number 726999.