This is how billionaires enjoy super-low 20% taxes

Marc Lasry
David A. Grogan | CNBC

For some, the only thing worse than filing taxes is knowing that others making millions of dollars are paying half the rate.

That's what has long infuriated critics of something called "carried interest," a rule that lets the managers of some private investment funds pay a long-term capital gains rate—usually 20 percent—on the money they make over the year on behalf of their clients. Even though the investment profits are how they're paid—hedge, private equity and venture capital fund managers often don't draw much of a salary—they don't get hit with the top income tax rate of 39.6 percent.

A small but growing group of investment managers thinks that needs to change.

"Taxing carried interest at the same rate as ordinary income is not unreasonable to me," said Marc Lasry, CEO and co-founder of $13.2 billion hedge and private equity fund firm Avenue Capital Group.