Mr. Chair, yes, I'll make a start.
One of the things the CRA has done is to publish a series of tax gap studies. When you talk about offshore, there's definitely offshoring by multinationals and there's offshoring by high-net-worth individuals. For the individuals, I think our estimate was $800 million to $3 billion. The variability in that estimate underscores the difficulty of estimating something that people are deliberately trying to hide.
In relation to multinationals, it seemed to me that our estimate said there could be $16 billion in tax unpaid by multinationals, half or $8 billion of which the CRA identified and sought to make them pay. You're in the range of $11 billion at the outer edge, with CRA maybe finding half of it. I think those are order-of-magnitude estimates that are enough to frame it. I don't think those are accounting-level details.
I will also say that we've been tracking voluntary tax paid by taxpayers—and those payments were greatly exceeding GDP. A lot of factors go into tax revenue. Tax revenue is a trailing, lagging indicator. Those revenues were pretty good last year, despite COVID, because they lag. There is lots of multi-year stuff from the companies.
Over the last five years, the tax paid voluntarily by multinationals was greatly exceeding GDP, sending at least to me the message that multinationals were getting the message and cleaning up their act, but there continue to be far too many multinationals with an effective tax rate that approaches zero, so there continues to be a problem.
Hopefully I've explained it as best I can in terms of the CRA data or the numbers we look at.