From this story
" Corporate profits reported to the I.R.S. in 1998 were $155 billion less than those reported to shareholders, according to Mihir A. Desai, a Harvard economist. His study and others suggest that tax shelters may be the primary reason for this difference, which is costing the government as much as $54 billion in taxes each year."
"The 10,000 or so largest companies paid 20.3 percent of their 1999 profits in federal income taxes, while the next tier of companies paid at a 30.9 percent rate, according to an I.R.S. analysis of corporate tax returns for the year. The largest companies had 26 times the profits of the second tier of companies, which paid income taxes at a rate 50 percent higher than the largest companies, the I.R.S. data shows."
Not that we didn't know it already, but to see it in black and white. Man, that's enough to fund the war on terror!