Still, it can be tough to keep a bank account if you're an American living in any country. "We're even hearing of some American banks closing accounts of Americans because they live overseas," McKeegan says.

Be Persistent

If you're an American expat and you have a bank account or have recently moved and need to get one, Michele Moore Duhen advises patience. Duhen relocated from Boston to London in April. She was able to open a bank account at Barclays, but it took some effort.

"My passport wasn't enough. They wanted bills proving I lived where my flat contract stated I lived. But you can't set up for bills until you have a bank card," Duhen says.

It took her about 10 days and several back and forth trips to the bank with various pieces of paperwork before she and her husband, a French citizen, could get accounts.

Don't assume that if a bank shuts your account you do not have other options in the same country. Darryl Daugherty, a due diligence specialist from Baltimore, says fellow Americans are having trouble opening accounts in Bangkok, where he has lived for 13 years.

"It's not yet insurmountable," Daugherty says - you just have to keep checking around for friendlier banks, he adds.

Renounce Your Citizenship

Renouncing U.S. citizenship is a drastic measure -- and surely an unintended consequence of FATCA. But McKeegan says he has seen American taxpayers doing that.

"It's not just the super rich doing it," McKeegan says. "We're talking average, middle-class people, people teaching English as a second language and doing freelance jobs making $30,000 to $50,000 a year, simply because of the fact that they can't open locked bank accounts."