"Trump's returns would show how active he and his businesses are globally," says a reporter who viewed the billionaire businessman's federal tax returns approximately 10 years ago
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Donald Trump has come under fire for his ongoing refusal to release his tax returns, with a blunt “It’s none of your business.” And even though he maintains that there’s “nothing to learn” from the returns, experts say they contain plenty of information voters should know about the billionaire businessman.

Let’s start with someone who has actually seen Trump’s tax returns. Bloomberg View executive editor Timothy L. O’Brien viewed Trump’s federal tax returns approximately 10 years ago, after the real estate mogul sued O’Brien for libel. “I think there probably are some things to be learned from them despite Trump’s statements to the contrary,” O’Brien wrote in a recent article, before listing the following questions Trump’s returns could help clear up.

1. Income
O’Brien points out that “Trump has made the size of his fortune a centerpiece of his presidential campaign, implying that it’s a measure of his success as a businessman After Fortune‘s Shawn Tully dug into Trump’s financial disclosures with the Federal Election Commission and an accompanying personal balance sheet his campaign released, he noted in March that Trump ‘appears to have overstated his income, by a lot, which could be the reason he has so far tried to avoid releasing his returns.’ ”

2. Business Activities
“Trump has long claimed that his company, the Trump Organization, employs thousands of people. He has also criticized Fortune 500 companies for operating businesses overseas at the expense of jobs for U.S. workers,” O’Brien writes. “Trump’s returns would show how active he and his businesses are globally – and would help substantiate the actual size and scope of his operation.”

3. Charitable Giving
“Trump has said that he’s a generous benefactor to a variety of causes – especially war veterans – even though it’s been hard to find concrete evidence to support the assertion. Other examples of major philanthropic largess from Trump have also been elusive. Trump could release his tax returns and put the matter to rest.”

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4. Tax Planning

“There’s been global attention focused on the issue of how politicians and the wealthy use tax havens and shell companies to possibly hide parts of their fortunes from authorities. If released, Trump’s returns would make clear whether or not he used such vehicles.” For his part, Trump told ABC News on May 13, “I don’t have Swiss bank accounts. I don’t have offshore [accounts].”

5. Transparency and Accountability
“Trump is seeking the most powerful office in the world. Some of the potential conflicts of interest or financial pressures that may arise if he reaches the White House would get an early airing in a release of his tax returns. For the last 40 years, presidential candidates have released their returns. Trump, of course, has portrayed himself as the un-candidate, the guy who bucks convention. But disclosing tax returns is a valuable political tradition thats well worth preserving.”

While the tax returns won’t reveal Trump’s net worth, which has also been a point of contention (Trump says he’s worth $10 billion, outlets like Forbes have put his net worth at $4.5 billion), LawNewz editor Rachel Stockman tells ABC News, “It would give us a good indication, however, of the financial conditions of his various businesses.”

At the very least, the returns will shed light on “how he plays the game with taxes,” Joseph Thorndike, director of the Tax History Project at the nonprofit Tax Analysts, tells The Associated Press. “It’s a big piece of someone’s financial life. It’s completely opaque to us at this point.”

The tax collector in Trump’s part-time home of Palm Beach County, Florida, has also called for him to release his returns to the public. Anne Gannon, who oversees the collection of property taxes from Trump’s Mar-a-Lago estate, released the following statement on Monday:

“Since 1976, all major party presidential nominees have released their tax returns to the public in a sign of transparency and honesty. Florida voters deserve to know whether a candidate for president is paying a lower tax rate than a middle class family – and tax returns help confirm whether someone is telling the truth and playing by the same set of rules as everyone else.”

“As the presumptive GOP nominee, Mr. Trump should immediately release his tax returns to the public and show he has nothing to hide. Floridians deserve to know how much money Mr. Trump makes, what he does with it, and whether his tax rate is lower than that of a typical working family.”

Do Voters Care About Trump’s Tax Returns?

So experts seem to agree that voters should care about Trump’s tax returns – but do they?

Trump told the Associated Press Tuesday night that he wouldn’t release his returns before the general election unless an IRS audit of his finances was complete. He added that “there’s nothing to learn from them” and that he doesn’t believe voters are interested.

Trump clarified his position on Wednesday, telling Fox News host Greta Van Susteren that he would in fact release his returns, hopefully by November. “I’ll release. Hopefully before the election I’ll release. And I’d like to release,” he said.

Here’s a sample of the reaction on Twitter.

Many loyal Trump supporters say they don’t care about Trump’s tax returns:

Others say Trump’s failure to release his returns weakens his stance as a Washington “outsider”:

And as for Mitt Romney – who has hit Trump hard for withholding his tax returns from the public – well, he’s still waiting.