The plan's main selling point is a zero-tax rate for individuals making less than $25,000 and couples making less than $50,000. While nearly half of Americans already pay no income taxes, Trump said the change would eliminate taxes for an additional 31 million Americans.

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At the same time, he said the plan would take away deductions and "loopholes" that are mainly exploited by the wealthy. That includes eliminating the so-called "carried interest" loophole used by hedge-funders and private equity chiefs.

"There will be people in the very upper echelons that won't be thrilled with this because we're taking away their deductions," Trump said.

He added that unlike some of his other opponents, specifically mentioning Hillary Clintion and Jeb Bush, he doesn't receive campaign money from rich donors who have sought to preserve their deductions.

Yet a close look at his proposal — which still lacks many basic details — suggests that similar to the Bush plan, the majority of the benefits would flow to the wealthy. In some ways, it could be even more generous.