But many tax-fairness advocates say that comparison is mathematically unsound. In addition to the current 35 percent tax on corporate profits, any dividends paid by corporations are also taxed as investment income received by the shareholders who collect them, at rates up to 23.8 percent. But pass-through income is taxed only once, said Chuck Marr, director of federal tax policy at the Center on Budget and Policy Priorities.

“The notion that this plan would achieve parity is a false comparison,” Marr, a former economic adviser to Senate Democrats and the Clinton White House, said. “Most of the savings of this change would go to the wealthiest businesses and the top 1 percent. But politicians love to stand up and say they are defending small businesses, so I fear it’s an argument that isn’t going away.”

Meanwhile, budget hawks worry that the steep cut would cause massive increases to the federal deficit -- as much as $1.5 trillion over the next decade, according to the conservative Tax Foundation. Gauging the precise costs and benefits of Trump’s tax plan is difficult because the administration has released few details about how it would be implemented.

Trump’s Businesses

Given that about 70 percent of pass-through income comes from banks, hedge funds and holding companies, the cut would be a boon for the financial services industry and many of the wealthiest taxpayers. Because Trump’s business interests derive millions in earnings from real estate, critics have accused the President of proposing a tax windfall for himself.

“Trump is seeking to dramatically reduce his own tax bill,” said Frank Clemente, executive director of Americans for Tax Fairness, a left-leaning advocacy group.

White House spokesman Sean Spicer brushed aside that concern Thursday, saying that average taxpayers are far more interested in how Trump’s plan would affect their own pocketbooks.

“I would guess that most Americans would applaud what the president is doing to spur economic growth and job creation in this country,” Spicer said.

Treasury Secretary Steven Mnuchin has pledged that the new pass-through rate would be implemented in a way that “won’t be a loophole for rich people who should be paying higher rates,” but has not released any details about rules that might deter abuse.

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