CRA will apply Canadian GAAP to financial statements prepared under IFRS in determining whether there is contributed surplus for thin cap purposes

CRA states in IT-59R, para. 8, that the determination of the contributed surplus (and retained earnings) of a corporation for thin cap purposes is governed by GAAP.

Where the Canadian corporation prepares its financial statements under IFRS (which do not use the concept of contributed surplus), CRA will recognize an amount reflected in the corporation's "equity reserves" as contributed surplus if it arose on a contribution of capital and it would be categorized as contributed surplus under (private company) Canadian GAAP.

Neal Armstrong.  Summary of 5 December 2012 T.I. 2012-0445891E5 under s. 18(4).