And it’s in the WSJ of all places. This editorial shows how the numbers are bogus, and deliberately so.
Bruce Bartlett’s basic points:

• This idea originally sprung from the head of Scientology, because of their clashes with the IRS^¹.
• It assumes growth rates in the US economy that appear to come from the planet Skaro.
• They use very bad math to misquote the percentage of tax^².
• It has the federal government paying the tax to artificially inflate revenues.
• It applies the tax to everything, including education and health care.
• It creates a de facto national welfare program.^³
• It understates the rate needed to balance the budget.

It should be noted that this Mr. Bartlett was senior economic staff under Bush I, this is no Democratic partisan here.

¹Basically they claim that a 30% tax is a 23% tax by figuring it backward. If you take $1.00 and add 30%, you have $1.30, but $0.30 is only 23% of 1.30.
^²The required tax rate for this to replace revenues 57%, it goes up to 64% if it exempts things like food, education, and health care, and 89% if there are problems with evasion.
^³It creates a transfer payment system in which people get money back on a weekly basis depending on wages.