Corporations don't pay 35 percent in taxes or anywhere close to it as GOP presidential hopeful Rick Santorum suggests, according to legendary investor Warren Buffett.

In a Wall Street Journal opinion piece, Santorum writes that "the corporate tax rate should be halved, to a flat rate of 17.5 percent. Corporations should be allowed to expense all business equipment and investment. Taxes on corporate earnings repatriated from overseas should be eliminated to bring home manufacturing."

That's not accurate, Buffett tells CNBC.

While the tax rate Santorum is proposing might not be a bad one, the 35 percent number is, in reality, very inflated.

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"What the rate should be are rates that bring in about 18.5 or so percent of GDP as revenue. Now we've had rates like that throughout most of post-World War II period. It's not impossible," Buffett says.

Over the last decade, corporate tax rates have fallen, while profits have risen.

"The interesting thing about the corporate rate is the corporate profits as a percentage of GDP last year were the highest or just about the highest in the last 50 years, at over 10 percent of GDP," Buffet says.

"That's higher than we've seen in 50 years."

Corporate taxes, on the other hand, came to about 1.2 percent of GDP.

"That's about the lowest we've seen so, our corporate tax rate last year effectively, in terms of taxes paid for the United States, was around 12 percent, which is well below those existing in most of the industrialized countries around the world. So, it is a myth that the American corporations are paying 35 percent or anything like it."

Turning to fiscal policy, Buffett says both Republicans and Democrats agree on the need to raise revenue and cut spending, although political posturing at present is preventing both parties publicly agreeing on a solution.

"We will have a growing pie but a growing pie isn't going to solve the deficit that's 9 percent or 8 percent of GDP. It never has and it never will," Buffett says of those who favor lowering the tax rate and broadening the base without raising revenue.

"Almost everybody says some of it has to come from expenditures and some of it has to come from revenues. The biggest problem you have is that Republicans and Democrats agree on that but they all want the other guy to go first. The Republicans and the Democrats to go first on expenditures, the Democrats want the Republicans to go first on revenue and they just feel that there is a tactical advantage in the other guy going first so they can shoot it down and say how terrible it is."

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