The delta between the 11%, 15%, or 17% numbers, and the 30%-50% I gave, is that the low values are for replacement of the existing federal income tax only. The 30% rate is what you'd arrive at if all current payroll deductions were added to the income tax deduction, and current state and local sales tax -- it would be the effective total sales tax rate. The 50% rate is effectively the total tax burden.

Calculating that last is tricky, as the taxes are rolled into many different collection mechanisms and jurisdictions. Given that there are single states with over 2,000 tax assessing bodies (Illinois comes to mind), it would be difficult to get a final number. I'm pretty comfortable with the idea that the final value is in the 40-50% range. 30% was a value tossed out by Chris Farrel on MPR's "Sound Money" radio show some months back.