I have been looking for this for a long time but there was a series of meeting back in 2000 between official in then Canadian Finance Minister’s Paul Martin’s Office and US Treasury Secretary Larry Summers over US Canada cross border migration. I was led to believe there was a joint statement by both the US and Canada at the time but most of the statement is quoted from Paul Martin. (The press release is rather interesting fodder as to whether the current government of Canada is any better on these issues than the previous).
For individuals, the changes will ensure the appropriate tax treatment of an emigrant’s gains. Specifically, where one country’s tax rules treat an individual as having disposed of a property immediately before the individual emigrates to the other country, the individual will be able to choose to be treated under the other country’s rules as also having disposed of and reacquired the property at its fair market value.
In most cases, this will mean that no tax is payable in the destination country on any pre-emigration gain. Where tax is payable in the destination country – for example, where the property in question is real estate situated in that country – the new rule will ensure appropriate tax crediting.
What I understand this to be is there is no negative effects as a matter a Canadian tax policy for a someone resident in Canada who renounces there US citizenship and has to pay exit tax.(The US Treasury going all the way back to 1995 had been pushing the “HEART” style exit tax as a preferred policy). My biggest disappointment is there seems to be no remarks or specific commitments from anyone in the US government at the time.