-——The study covered 2006, the most recent for which the IRS said it had data available. The amount of underpaid taxes far exceeded the size of the entire federal budget deficit at the time.-——
How soon we forget that under Bush deficits were only billionc and not trillions like today
That 450 billion MUST include penalties .....
It means that that is what is owed before any deductions are taken and the amount owed is computed at the highest rate.