In 2010 the United States passed the Foreign Account Tax Compliance Act ("FATCA") imposing on non-us financial institutions the obligation to report to the US details of foreign bank accounts held by United States citizens and residents, whereever they might reside.  Under FATCA, foreign financial institutions faced the conundrum of complying with US law requiring disclosure, or the foreign domestic laws requiring confidentiality. To allow Canadian banks to comply, and to comply with the provisions of the Canada - United States Income Tax Convention, Canada entered into an agreement with the United States and passed legislation requiring Canadian banks to disclose the required information to the Canada Revenue Agency.  The CRA upon receipt of this information will disclose the records to the IRS in accordance with the exchange of information provisions of the Convention.

In 2014, two Amercican citizens who were Canadian residents filed an application in the Federal Court of Appeal seeking a declaration that Canada's legislation to share this information with the US was unconstitutional.  On September 16, 2015, the FCA released its decision (http://goo.gl/mdaH5S) upholding the Canadian law, and thereby affirming the obligation of Canadian financial institutions to report details of accounts held by United States citizens and to disclose this information to the IRS.