For honest money, there's more to consider.
Step 2: Decide whether to tell the IRS.
U.S. citizens are supposed to pay taxes no matter where their money is. But the IRS can't tax what it doesn't know about, and the odds of getting caught offshore have been slim. But beware — that's changing.
The government has landed some big fish — notably the largest Swiss bank, UBS AG— and tax cheats are getting scooped up in the net.
In an unprecedented break from Swiss legal tradition, UBS turned over the names of more than 4,000 suspected U.S. tax evaders in 2010 as part of a deal to settle conspiracy charges. Since then, the United States has been going after those people, charging more Swiss bankers with conspiracy, and leaning on Switzerland to name more names.
Other names came from a bank employee-turned-informant at the LGT Bank in Liechtenstein. And the IRS has been tracking down holders of credit cards issued from Caribbean hideaways, because the cards are a popular way to tap secret funds.
"The noose is tightening on those who want to hide money overseas," said J. Richard Harvey, a former senior adviser to the IRS commissioner.
Pressure to report Americans' holdings will increase substantially next year under a new U.S. law that imposes financial penalties on foreign banks and investment funds that don't comply. Some tax haven banks may skirt it completely, however. If they don't make any U.S. investments they can avoid the penalties.
When the IRS offered amnesty in 2009 and 2011, more than 33,000 tax dodgers came in from the cold, yielding $4.4 billion. A new round in the program opened in January.
Step 3: Look for legal ways to pare taxes.
Here it gets complicated.
For corporations, foundations, pension funds and others, controversial offshore maneuvers can help defer or avoid some taxes. For example, a corporation transfers a lucrative chunk of its business to a foreign subsidiary in a low-tax country. Or a nonprofit group puts otherwise taxable investments offshore.
"There's a thin line between tax avoidance and evasion," said Rebecca Wilkins, a senior counsel at Citizens for Tax Justice, which opposes corporate loopholes. "A lot of these transactions might not stand up in court if the IRS had the resources to pursue them."
Private equity and hedge funds flock to the Cayman Islands, which offer tax advantages for fund managers and some of their foreign and nonprofit investors. Setting up shop — usually nothing more than a mail drop — in these freewheeling environs also allows them to escape the tighter financial regulations of the U.S. and other nations. Some critics say that contributed to the global financial crisis.
Romney, the multimillionaire front-runner for the Republican presidential nomination, has disclosed numerous offshore investments.
His financial filings included at least six Cayman-based funds, worth between $7 million and $32 million, run by Bain Capital, the private equity powerhouse he once led. More than a dozen other funds based in the Caymans and Bermuda showed up on his 2010 federal tax returns. His campaign says he pays the same taxes he would if they were based in the United States.
Romney also had a UBS bank account in Switzerland, but it was closed in 2010 as he prepared to run for president.
Step 4: Consider other motives.
Some people want to hide wealth from spouses or business partners; doctors worry about malpractice suits; others think creditors or the government might try to seize their assets.
Wealthy residents of oppressive countries may feel safer with their savings elsewhere. Dictators, fearing revolt, often do, too.