The inter-governmental agreement (IGA) between the USA and Canada which will enforce FATCA in Canada has an interesting line on page 27:
With respect to New Individual Accounts not described in paragraph A of this section, upon account opening (or within 90 days after the end of the calendar year in which the account ceases to be described in paragraph A of this section), the Reporting Canadian Financial Institution must obtain a self-certification, which may be part of the account opening documentation, that allows the Reporting Canadian Financial Institution to determine whether the Account Holder is resident in the United States for tax purposes (for this purpose, a U.S. citizen is considered to be resident in the United States for tax purposes, even if the Account Holder is also a tax resident of another jurisdiction) Continue reading