First, Cain's 9-9-9 plan taxes employee payroll 9% and the employee pays 9% in income tax so there's 18% right off the top for all labor in the US the government walks away with. This is the minor point... Just making it clear.
Second, Cain's 9-9-9 plan taxes materials/goods that business buy that don't originate in the US 9% essentially making it a 9% tariff on all imports. This is dangerous. Nearly all semiconductors and other base components - including around 60% of our oil - is imported. Are we really going to tax Canadian and Mexican oil 9%? Computers, TV’s, phones, etc. will have an almost instant 9% cost increase.
Now where that's particularly dangerous. What happens if other countries decide to do the same thing with our products they buy? We export more than many people know. Like number 1 in the world. Trade barriers are a bad plan and could set off an economic chain reaction of international trade retaliation.
The 9% import tariff comes from the fact that the cost of materials businesses use to produce their products are counted as the cost of doing business and not taxed when those materials are domestically sourced. Imported supplies are not counted in the cost producing goods and are taxed. In fact for products manufactured in the US using some significant portion of imported parts and then that product is sold world wide it encourages manufacturers to move their plants outside the US so they don't have to pay 9% to import components that their competitors outside the US don't have to pay.
Please correct me if I'm wrong.
The 30 percent corporate tax dissuades companies that do business in American from locating themselves in America. Cutting this down to 9, would make it much more appealing for them to do so.
As for importation, 22 percent of every good (sometimes more) is consumed by taxes, irrespective of importation or no. These are all hidden taxes built into the price. All of these go away. So while the sales tax will increase the price by 9 percent, the actual price would come down. America would be closer to the actual world price of imported goods, which makes them a more attractive destination to sell.