Let's say, for example, that a U.S. multinational has a Canadian subsidiary and seeks to sell that subsidiary to a purchaser. Prior to this change those shares would have been taxable Canadian property. The U.S. multinational likely would not have been taxable on that sale because it would have been protected from Canadian tax under the treaty with the U.S., but it still would have been required to go to Revenue Canada to get a clearance certificate in advance of the sale of those shares. So one of the effects of this change is this compliance will no longer be required.
On April 22nd, 2010. See this statement in context.