WASHINGTON (AP) — Republican presidential candidate Donald Trump is refusing to disclose even what tax rate he pays until an IRS audit of his tax returns is complete.

"It's none of your business," he told ABC's "Good Morning America" when asked what tax rate he pays in a phone interview Friday. "You'll see it when I release. But I fight very hard to pay as little tax as possible."

Trump has refused to release his tax returns until, he says, an IRS audit is done. He says he will "gladly" release them when that happens, but makes no guarantees it will happen before Election Day.

In an interview with The Associated Press this week, Trump said he hoped the audit would be done in time but feels no obligation to the public to get the returns out before people vote.

"I really don't, and I'll tell you why," he said. "You don't learn anything from a tax return. I think nobody knows more about taxes than I do, maybe in the history of the world. Nobody knows more about taxes. You can learn very little from a tax return." He also said he doesn't believe voters have much interest in the issue.

Still, he said, "I hope it gets finished soon. And if it gets finished soon I put it out immediately 'cause there's nothing there. But until you get finished, you won't."

In fact, tax experts say the documents could provide significant insights into Trump's income and wealth, how much he gives to charity, the health of his businesses and, overall, how Trump plays the tax game.

Trump also said on ABC he doesn't keep money in Swiss banks or offshore accounts.