Mitt Romney was excoriated during the 2012 presidential campaign for paying $4.9 million in federal income tax, or an average of just 14 percent of his adjusted gross income, in the two years for which he released returns.

No one should be surprised, though, if Donald J. Trump has paid far less — perhaps even zero federal income tax in some years. Indeed, that’s the expectation of numerous real estate and tax professionals I’ve interviewed in recent weeks.

Even with hundreds of millions in gross revenue from his vast real estate empire, “it’s both possible and legal that Donald Trump would pay little or no income tax,” said Len Green, an accountant and chairman of the Green Group, a tax and accounting advisory firm. Mr. Green is also a real estate investor, teaches at Babson College and is the author of the forthcoming “The Entrepreneur’s Playbook.”

“I would expect he’s paying little or no tax,” agreed Steven M. Rosenthal, a veteran tax lawyer and senior fellow at the Urban-Brookings Tax Policy center.