I'm going to sound like an asshat for not being 100% sure on my figures.
But I'm 90% sure that in a recent story, one of the big Wall Street firms was listed as spending like 5 BILLION, with a 'B' dollars on people to make sure they stay in compliance with the absurd tax code. I really want to find the story now, because I remember reading it and being absolutely astonished at how much money was wasted on their army of accountants or whatever the hell all goes in to tax compliance.
I shall look and provide linkage!
Perhaps it'll be a place to start.
EDIT: Ok I think I was off, and my figure might have been all the big Wall Street firms, not just one.
Take a look at this link:
http://linder.house.gov/_pdfs/WSJFoxCNN.pdf