It is unclear whether Canadian private trusts can opt into FATCA reporting to CRA to avoid potential U.S. withholding

Certain investment vehicles such as private trusts with U.S. beneficiaries are not financial institutions under s. 263 of the Act but are financial institutions under the Intergovernmental Agreement respecting FATCA. Accordingly, they could become subject to FATCA withholding.

It is unclear that they could avoid this result by voluntarily opting into the Canadian domestic FATCA reporting regime. Furthermore, if they did so, it is unclear that they would be protected from liability for breach of privacy as such disclosure of confidential information would not be required by Canadian law.

Henry Chong, "Canada and FATCA", Tax Management International Journal, 2014, p. 527 under Canada-U.S. IGA, Art. 5, s. 2.