If you get rid of all these giveaways and loopholes and deductions and credits, then you can sharply lower the rates.

It was an easy thing to tax for a young country. And then gradually we moved to property taxes, manufacturing taxes, and the income tax was the answer to a populist demand: Let's go after the rich guys. We got into World War I, and they raised the rates and started taxing the rich. Then we got into World War II, and that's when they taxed everybody, because they just needed more revenue.

Starting in the '80s or so, after the United States sharply cut its rates, other countries decided they better do it too, and here's how you do it: you just wipe out the exemptions, the deductions, the credits, the depreciation allowances. And people complain, "Oh my God, it's terrible," but you give them much lower rates and you give them an easier form to file, and people accept that tradeoff.

Professor Eric Zolt of UCLA, said to me, "The VAT is such a good idea, mark my words, within five years, the U.S. will have a VAT." Then he said, "Of course, I've been saying that for 20 years."

The higher the rate, the more interest there is in avoiding the tax. Either you move or you shift your profits overseas, as American corporations have proven very good at doing.

Mortgage is one of the most popular deductions. It costs the Treasury about $103 billion a year. Now that's money we could use to treat wounded veterans or reduce the deficit or fill the border. Instead, we give it a subsidy to homeowners, and it goes mainly to the richest homeowners in America, because only one third of Americans itemize their deductions. It doesn't work. Many countries have gotten rid of the mortgage interest deduction. Almost all of them have higher homeownership rates than we do.

We have the most expensive compliance system in the world. The IRS brags that they spend 35 cents for every $100 they collect. They're very efficient collectors. And the reason is they stick the real cost on you and me.