Republican presidential candidate Donald Trump delivers an economic policy speech to the Detroit Economic Club on Aug. 8 in Detroit. (Evan Vucci/AP)

A little-noticed provision in Donald Trump’s tax reform plan has the potential to deliver a large tax cut to companies in the Republican presidential nominee’s vast business empire, experts say.

Trump’s plan would dramatically reduce taxes on what is known in tax circles as “pass-through” entities, which do not pay corporate income taxes, but whose owners are taxed at individual rates on their share of profits. Those entities are the most common structure for small businesses and increasingly popular for larger ones as well. They are also a cornerstone of the Trump Organization. On his 2015 presidential financial disclosure report, Trump listed holdings of more than 200 limited liability corporations, which is a form of pass-through.

There is no indication that Trump designed his tax plan to benefit his own companies. “It wasn’t something we took into consideration when we made this plan,” Trump economic policy adviser Stephen Moore said.

Still, the provision highlights the tensions between Trump’s policy proposals and his personal financial interests. He would also benefit from his proposals to cut top income tax rates and eliminate federal taxes on inherited wealth, which now are imposed when a couple has more than $10.9 million in assets. Other wealthy candidates advocating for tax cuts similarly benefit from those types of proposals.

"It’s a really nice deal” for Trump and pass-through owners like him, said Roberton Williams, a senior fellow at the nonpartisan Tax Policy Center.

Trump sketched an outline of the revised tax plan on Monday in Detroit, and advisers say he will fill in more details in the weeks to come. A campaign spokeswoman did not reply to a request for comment.

Other Republicans and some business lobbying groups have long pushed to reduce taxes on pass-throughs, but what’s notable about Trump’s proposal is that it goes much further than any other recent GOP nominee's.

Trump would tax pass-through income at a rate of 15 percent, compared to the 40 percent personal income tax rate a wealthy business owner would pay today. He is the first GOP nominee to propose a specific pass-through rate. Others have simply lowered the top income tax rate, which would have the effect of lowering the pass-through rate as well. Mitt Romney, the party’s 2012 nominee, would have set a top rate of 28 percent. John McCain and George W. Bush wanted to tax it at 35 and 33 percent, respectively.

While the proposal could benefit Trump, tax lobbyists say the plan would also help many small-business owners. Organizing as pass-throughs currently gives those owners a tax advantage against traditional corporations — and under Trump’s plan, that advantage would grow.

The National Federation for Independent Business, a small-business lobbying group, praised the plan this week, saying it would “encourage more small-business investment, job creation, and economic growth.”

But critics say the changes could distort business investment, create new incentives for tax-evasion and shower benefits disproportionately on the wealthiest Americans.

Trump “personifies the problems with pass-throughs, in a really clean way,” said Brendan Duke, the associate director for economic policy at the liberal Center for American Progress think tank, which on Wednesday released a report on the practice. “He’s proposed to make the problem far worse and in a way that would be a big benefit to him.”

Moore, the Trump adviser, called the pass-through plan “good policy” and “a home run” politically, allowing Trump to say he would cut taxes on small business dramatically lower than Democrat Hillary Clinton would.

He acknowledged critics saying the changes would benefit high-income earners. “The truth is, a lot of high-income people are small-business owners,” Moore said. “They’re going to get a tax break. Our view is that they’re going to plow that right back into their businesses.”

At a rally in Detroit Aug. 8, Republican presidential candidate Donald Trump outlined what he would do as president to take the U.S. economy to "amazing new heights." (Sarah Parnass/The Washington Post)

A study released last year by a team of economists, led by Michael Cooper of the Treasury Department, found that pass-through entities now account for half of the business income in the United States, up from a quarter in 1980.

Pass-through income is taxed at a lower rate than income from traditional corporations, including publicly traded ones, that are subject to the corporate income tax. The top corporate rate is currently 35 percent, though many businesses take advantage of deductions to pay a much lower effective rate. But the total amount of tax paid is still higher — shareholders also pay taxes on dividends and capital gains generated by the companies.

The new Center for American Progress study says that despite its reputation as a small-business tool, 70 percent of pass-through income flows to large businesses and eventually into the hands of the top earners. That’s because so many financial firms are organized as pass-throughs, and so many of America’s top earners work in such firms.

The CAP authors estimate that the rise of pass-throughs cost the federal government nearly $800 billion in tax revenue between 2003-2012. They propose making large pass-throughs pay the same tax rate that traditional corporations do now.

The Trump plan would do the opposite: It would reduce tax revenue from corporate and pass-through income by reducing the tax rate on both to 15 percent. This is a more aggressive version of a sort of tax “harmonization” that other reform proposals have aimed for. The House GOP tax plan, for example, would set the corporate income tax rate at 20 percent and the maximum pass-through rate at 25 percent.

Trump and his economic advisers contend their rate cuts would energize economic growth and generate enough new investment and business activity to make up for most or all of the reduced tax revenues.

Independent analysts have not agreed with that assessment. The Tax Foundation, a nonpartisan group that typically favors tax cuts, previously estimated that a version of Trump’s tax plan, including business and personal tax changes, would reduce revenues by $10 trillion over a decade, even after factoring in faster growth. Trump is revising his plan to reduce those estimated costs, but he appears to have rejected appeals from some economic advisers to do so in part by changing his treatment of pass-through income.

Kyle Pomerleau, director of federal programs for the Tax Foundation, said Trump’s plan would effectively double the tax-rate advantage pass-throughs enjoy over traditional corporations.

The change would encourage businesses to make investment decisions “based on an arbitrary difference in the tax system,” Pomerleau said. He added: “It’s a pretty big tax cut, but it doesn’t result in a significant amount of economic growth.”

Trump’s companies would appear to benefit significantly from that cut, though it is difficult to say exactly how much since they do not publicly report their finances. Trump has declined to release his personal income tax filings, and in the past, Trump has boasted of his strategies to minimize his tax payments.

In a March letter that accompanied his financial disclosure filing, Trump’s lawyers allude to the degree to which his income flows largely from two types of pass-throughs.

“You hold interests as the sole or principal owner in approximately 500 separate entities,” the lawyers write. “These entities are referred to and do business as The Trump Organization. … Because you operate these businesses almost exclusively through sole proprietorships and/or closely held partnerships, your personal federal income tax returns are inordinately large and complex for an individual.”

Simplifying the tax code has long been a goal of tax-reform advocates, but the efforts have been hampered, in part, by arguments over whether small and large businesses should pay different rates on their incomes. Some conservative economists say Trump’s plan could help resolve those arguments and stands in contrast to Clinton’s proposals to raise some taxes that businesses pay.

“Matching the corporate and pass-through rates does not automatically meet any economic efficiency or fairness goal,” said Doug Holtz-Eakin, a former head of the Congressional Budget Office and top economic adviser to McCain in 2008, “but it does lead to a truce in the war between big and small businesses.”

One of Romney’s top advisers in 2012, Columbia Business School Dean Glenn Hubbard, said he thinks of Trump’s plan as “indicating a direction toward a tax system much more favorable to business income and investment, while Secretary Clinton would raises taxes on corporate and individual incomes. The details of both plans would change as they hit the messy world of actual tax legislation, but the directional differences are pretty clear.”