Retiring abroad may sound idyllic. But those who fall short on financial planning can pay a big price. For the 380,000 retirees who live abroad, according to the Social Security Administration—up from 307,000 in 2008—the potential missteps are numerous. Amid a U.S. crackdown on money laundering, tax evasion and non-compliance with tax-reporting obligations, some expats are being cut off by their banks and brokerage firms. Others are running afoul of the Internal Revenue Service. Many are discovering that tax treaties don't always fully protect them from double taxation. "People rarely understand the complexity of cross-border moves," says Jonathan Lachowitz, founder...
