Donald Trump claims IRS is preventing release of tax returns

Donald Trump's rivals pressed him on his tax returns at Thursday's GOP debate, claiming he has something to hide.

If Donald Trump released his tax returns, they would show a better picture of his tax rate, his income and also give insight into his charitable donations, but the GOP frontrunner says he can't because the Internal Revenue Service is keeping him from releasing them, reports CBS News correspondent Julianna Goldman.

Mitt Romney: Donald Trump may have "bombshell" tax issue

"For many years, I've been audited every year - 12 years or something like that. Every year they audit me, audit me, audit me," Trump said.

"The only reason he's not releasing them is he's afraid that he'll get hit," Cruz said.

But there's actually no rule preventing Trump form releasing them, whether he's being audited or not - something the IRS can't confirm. Federal law prohibits them from disclosing if a private citizen is being audited.

"I give a lot of money to people and charities and everything," Trump said. "I love people, I think I'm a nice person, I want to be a nice person."

His campaign claims he has given away over $100 million. Trump's tax returns would provide a complete picture.

"And that's the part that's really tricky. And you know - nobody is required to disclose their private donations but we just don't have a sense of whether that's true or not," said Stacy Palmer, editor of "The Chronicle of Philanthropy." "There haven't been announcements from the recipients of the organizations, you know. Certainly when Harvard gets a big gift and says we're naming a school after somebody, they say it's $350 million that we've received and we all know about that and have that verified. You don't have that with Trump."

To get a better sense of Trump's philanthropy, CBS News turned to the most recent five years of tax filings for his Donald J. Trump foundation. Over that period, it gave away just over $5.2 million.

The list of grant recipients skews toward celebrity and includes charities associated with Joe Torre, Arnold Palmer, Jenny McCarthy and Larry King.

In 2014, donations from the Trump Foundation dropped 35 percent from the year before.

"Anybody who gives money is a philanthropist. So, you know, a Girl Scout who sells cookies is a philanthropist in a lot of people's definition," Palmer said. "Is he one of the biggest donors or the most influential ones in American philanthropy? No. We don't see any evidence of that."

More than 60 percent of the money that the Donald J. Trump Foundation gives away does not come from the billionaire himself, but from outside donors. One wealthy donor, a New York ticket broker, gave nearly $1.9 million to the foundation.

As for Trump's recent charity drive for vets, he said he's distributed millions, but his campaign won't provide a comprehensive list of where the money has gone.