I think most of the research that has been done on the underground economy shows that as tax rates rise, the more punitive the tax rate is regarded by businesses or by average citizens, the more propensity there is for some tax revenue to basically be foregone because things go underground.
Canada doesn't have a huge problem with the underground economy at the moment and that's a good thing. I also operate from the assumption that the vast majority of small business owners and average Canadians dutifully pay their taxes because they feel it's their responsibility and nothing upsets a small business owner more than having their competitor working under the table.
I can say for sure that one of the most effective ways to reduce the size and scope of the underground economy is reducing taxation in general. The issue that our colleague from the Convenience Stores Association brought up I think shows that as taxes on tobacco were reduced—and that's not a position I'm advocating—so was the amount of underground economy in that industry reduced.