The Foreign Account Tax Compliance Act, or FATCA, became law in 2010. It requires financial institutions worldwide to report holdings of "U.S. persons" worth more than $50,000 to the IRS. 

Those institutions the IRS deems non-compliant could face a withholding tax of up to 30 percent. The law was designed to go after scofflaws that hide money in overseas accounts, and the IRS expects to collect $7.6 billion over the next decade because of it.