The 60-month exemption from Canadian exit tax is narrow

Where a UK resident with a share ISA (the UK equivalent of a TFSA) immigrates to Canada (becoming a temporary Canadian resident) and then emigrates less than 60 months later, the shares in his ISA will be exempted from Canadian exit tax if they were held at the time of his previous immigration, but not generally if they were subsequently acquired.

Neal Armstrong.  Summaries of 5 December 2013 T.I. 2013-0485661E5 under 128.1(1) and 128.1(4).