One of the main increases in revenue will be seen as a result of the currently "untaxed", namely illegal aliens, drug and arms dealers, cash under the table earners,etc., finally paying their share. Also, having done payroll for years, I can tell you that you can look at the amount withheld from your check for Soc Sec and see how much your employer will be saving, as that is the amount they must match, as well as 2.5% for Medicare.
So, as I see it, the reason it is called the Fair Tax is because, well, it's FAIR! I get really tired of standing in line at the grocery store behind Mr. Local Drug Dealer and his current honey paying for t-bones with an ebt card when even the infant is wearing high dollar sneaks and driving off in a Lexus SUV. Let him and everyone else pay his taxes in a more equitable manner.
The point for illegal activity has no validity. Under the fair tax, if I provide a legal service to a customer, I collect $130 and send $30 to the government and pocket $100. If a prostitute provides a service and collects $130, she is going to pocket the $130 and not submit the tax. These illegal activities are still cheating the system the exact same way they are today. No difference. Sure when they spend the money legally, taxes get paid. But that is what happens today. When a prostitute goes out to buy a car today, she pays all the embedded taxes in the car. Unless the fair tax is going to somehow get the prostitute to submit the sales tax on the money she collects, this claim that the fair tax captures the illegal economy is a bogus one.