His Corporate Tax is suspect because it implies the taxation of gross revenue, not gross profit. That would decimate most business. He needs to clarify the issue, but AFAICT, it appears to be so.
Like Nutmeg said, there's zero mention of spending *reductions*, which is tantamount. No mention of the 1 Trillion Defense budget. No mention of entitlement reform. No mention of the bloated Federal Government.
Going to a flat rate or sales tax is better, but that only addresses 1/10th of the problem. That isn't to say tax reform isn't critical - it is. But it's only one major problem amongst many.