You have to realize that the vast majority of income tax is deducted at source. Those are payments that come in with essentially no collection effort. We can try to find the numbers on how much is not actually deducted at source, but it's a relatively low amount. Also, generally in Canada I think the compliance rates tend to be pretty good compared with those in other countries. A large part of it is personal income tax, and most of that comes in automatically.
On June 19th, 2006. See this statement in context.