(CNN) When Donald Trump unveiled his tax-reform proposal on Wednesday in Indianapolis, he promised the audience that his plan wouldn't help people like him. At all.

"Our framework includes our explicit commitment that tax reform will protect low-income and middle-income households, not the wealthy and well-connected," Trump promised . "They can call me all they want. It's not going to help. I'm doing the right thing, and it's not good for me. Believe me."

You'll have to take his word for it because there is simply no way of checking to see if Trump is telling the truth about the tax plan's impact on his own bottom line. Why? Because Trump still hasn't released any of his personal tax returns, the first president in modern times to refuse to do so.

"What I think the American people are worried about is their own financial situation," Cohn said in one dodge. "I think what they're concerned about is when they go to work every week and they get their paycheck at the end of the week how much do they get to keep?"

Cohn's responses are broadly consistent with how Trump and his senior aides have long responded to his repeated refusal to release even a year's worth of tax returns. Trump has said that his most recent return is under audit and that, when that audit concludes, he will release the return. (Trump could release his returns even during an audit, of course, as Richard Nixon did in the early 1970s .)

Soon after he was elected, White House senior counselor Kellyanne Conway insisted that Trump would not be releasing his returns at all . "The White House response is that he's not going to release his tax returns," Conway said in an interview on ABC's "This Week." "We litigated this all through the election. People didn't care."

The White House walked those comments back but Conway's "gaffe" clearly had the ring of truth. Trump had defied repeated calls to release his returns during the campaign and clearly is convinced that voters don't care.

We don't have any way to prove that point. The 2016 exit poll didn't ask any questions about Trump's tax returns.

Here's what we do know: Even based on the limited tax information that has leaked out, the President could stand to save in excess of $1.1 billion under his new tax package , according to calculations made by the New York Times.

"Though it would not be reflected on his income tax return, Mr. Trump's proposal to eliminate the estate tax would generate the largest tax savings. If his assets — reportedly valued at $2.86 billion — were transferred after his death under today's rules, his estate would be taxed at about 40 percent. Repealing the federal estate tax could save his family about $1.1 billion, though it could still be subject to New York estate taxes."

That's a big chunk of change. And it makes clear that Trump's assertion that he would not benefit from his proposed tax cut is not likely true.

You can expect to hear lots (and lots) more about Trump's taxes in the coming months as Congress debates the tax reform plan.

Senate Minority Leader Chuck Schumer has made clear he views Trump's refusal to release his tax returns as a major stumbling block in the attempts to get tax reform done.

"It's going to be much harder to get tax reform done if the President doesn't disclose his taxes," Schumer said back in April. "For the very simple reason that when there is a provision in the bill, people are going to say, 'Oh, this is for President Trump and his business, not for the benefit of the American people.' Particularly when you have the sort of large real estate business that he has. There are all kinds of tax laws that affect it. If the President is interested in tax reform, he should release his tax returns because it's going to make it much harder to pass it without it."

That's an important point. As Republicans' failure to repeal and replace Obamacare makes clear, the 52 seats the party currently controls in the Senate leaves them very little margin for error. Being able to convince a Democrat or two to be for tax reform would certainly improve the chances of some sort of legislation passing.

And, in theory, this Democratic caucus should be ripe for the picking on the issue. After all, 10 Democrats up for reelection in 2018 represent states that Trump won in 2016 -- including five that he won by double digits. People like Heidi Heitkamp (North Dakota), Joe Donnelly (Indiana) and Joe Manchin (West Virginia) sit in states where it would make sense for them to find a way to be for some sort of Republican-led tax reform effort.

Trump's refusal to release even a year's worth of tax returns gives these Democrats an easy -- and politically palatable -- out. "I can't vote for something not knowing whether or not this will feather the president's own nest," you can imagine one of these Democrats saying.

On tax reform -- stop me if you've heard this one before -- Trump is his own worst enemy. His refusal to release any tax returns -- and his administration's shifting stories on why -- badly complicates what will already be a rocky road to turning this bill into a law.

None of that means, of course, that Trump will reverse himself on the taxes issue. He won't. Because he doesn't do that on anything. But, in the process, he's making things hard on himself -- and his party.