The pitch is seductive: trade an expensive U.S. suburb for a sunlit town in Portugal, Mexico or Thailand, where a Social Security check stretches two or three times as far. Plenty of Americans do it happily. But the ones who struggle usually tripped over the same handful of money rules — none of which the brochures mention.

You never stop paying U.S. taxes

Start with the big one. The United States taxes its citizens on their worldwide income no matter where they live — one of the very few countries that does, as the IRS spells out. Move to Lisbon, and you still file a U.S. return every year on your pensions, investments and any rental income back home.

Living abroad can also make you a tax resident of your new country — typically after spending more than 183 days a year there — which can mean owing tax to both governments on the same income. Tax treaties and foreign tax credits exist to soften that double bite, but they rarely erase it, and they add real complexity. (Tax residency is the status that makes a country entitled to tax your income; spend enough time somewhere and you usually acquire it.)

There is paperwork, too. Americans with foreign bank and investment accounts totaling $10,000 or more must file an annual FBAR (a Foreign Bank Account Report) with the Treasury, and larger holdings trigger additional IRS forms. The penalties for skipping them are severe. One side effect: because U.S. reporting rules are onerous, some foreign banks simply refuse American customers, making everyday banking abroad harder than expected.

Medicare stops at the border

Here is the rule that surprises people most: Medicare generally does not cover care outside the United States, according to Medicare.gov, apart from a few narrow exceptions. If you retire to Spain and need surgery, traditional Medicare pays nothing.

That is not necessarily a dealbreaker — healthcare in many popular destinations costs a fraction of U.S. prices, and expats typically buy local or international private insurance. But it means budgeting for coverage you assumed was already handled, and thinking through what happens in a serious emergency, where an evacuation or a flight home can be expensive.

Social Security travels — mostly

The better news: Social Security will generally pay benefits to retirees living abroad, the Social Security Administration confirms. But there are exceptions — the government cannot send payments to a handful of countries, notably Cuba and North Korea — so it's worth confirming your destination is on the approved list before you move.

The currency you don't control

Even with the taxes and healthcare sorted, there's a risk that runs quietly in the background: exchange rates. If your income arrives in U.S. dollars but your rent, food and medical bills are in pesos, reais or baht, then a weaker local currency is a windfall and a stronger one is a pay cut — without your income changing at all. Over a retirement that may last decades, those swings can meaningfully alter your standard of living, and they are hard for an individual to hedge cheaply. (Currency risk is the danger that a change in exchange rates raises your real cost of living when you earn and spend in different currencies.)

Doing it with eyes open

None of this makes retiring abroad a bad idea — thousands manage it well. It simply rewards planning over daydreaming: test-drive a country before selling the family home; keep a U.S. bank account to receive Social Security and handle taxes; hire a cross-border tax professional rather than guessing; confirm the visa and residency rules, which change often; and hold a cushion in dollars against currency swings.

Why it matters

For households, retiring overseas is one of the biggest financial decisions a person can make, and its pitfalls are administrative and easy to miss — not the cost of living everyone focuses on, but taxes, healthcare and exchange rates. For the broader picture, the appeal reflects real strain at home: the same U.S. costs — housing, medical care — that push some retirees to look abroad in the first place. Boursel gives no personal financial advice; the takeaway is that the dream is achievable, but it comes wrapped in rules that follow your passport across every border — and the retirees who thrive are the ones who counted them first.