Unless Donald Trump releases his tax returns, we should assume he is lying through his teeth about giving “millions” to charities and good causes.

We should assume that when he had a chance to show how much he really cared for veterans by giving some of his money to help them, he flipped them off.

And when he had a chance to show how much he supported, say, police officers or their families, or border patrol agents by contributing to their benevolent funds or even legal defense funds, he just let the phone ring.

And when he had a chance to show his compassion or generosity by giving money to other charitable causes, he told them to talk to the hand.

I can’t prove it for certain. You can’t prove a negative. But it’s time to stop letting cynical spin doctors take advantage of that principle. Trump can prove this assumption wrong by releasing his tax returns. If he doesn’t, the assumption will have to stand.

“ When people hide financial documents, there’s a reason for it. ”

Ironically, I would love to be wrong. I would love to be able to see that Trump has given a fortune to good causes, year after year. I would love to be stunned by the scale of his generosity. The reason? It might encourage other rich people — and other middle-class people, for that matter — to reach into their wallets more often as well.

Oh, and it might also give me a smidgen more hope about the man who has a one-in-three chance of becoming the next president. Donald Trump could be in the White House next January. He could control our nukes, our Special Forces and the awesome, terrifying panoply of the state. I would love it if he weren’t a sociopath.

But I dare not hope. Trump is hiding his tax returns.

If it looks, talks and quacks like a duck, it’s almost certainly a duck. And when it looks, talks and quacks like a billionaire going out of his way to hide the one legal document that could show how much he has given to charity over the years … well, work it out.

Every presidential candidate in modern times has shared his returns with voters, so that they could see he was on the up and up. Even Trump’s running mate, Mike Pence, has done so.

Can you imagine the news headlines if Hillary Clinton were hiding her tax returns? (Really. Just shut your eyes for a moment and just imagine it. Hilarious, isn’t it?)

Read: Trump Foundation’s purchase of Trump painting gives new meaning to art of the deal

This isn’t a sideshow. This goes to the heart of the Trump campaign. Donald Trump claims to be a rich guy who has the interests of ordinary people at heart. But if that were true, he would have shared generously of his fortune with deserving ordinary people over the years. I’ll bet most of the people reading this have done so, and they don’t have a fraction of Trump’s wealth.

If he hasn’t done that, then he isn’t a rich guy who has the interests of ordinary people at heart. He is a rich guy running for president out of vanity — oh, yeah, and so he can save his kids billions in inheritance taxes by abolishing them.

Donald Trump supporter punches protester at rally

I’ve been writing about finance for over 20 years, and over and over again I’ve found that when people hide financial details, they do it for a reason. That was true when Enron was shuffling derivatives into separate “special purpose vehicles” that didn’t show up on the balance sheet. It was true when Wall Street banks created mortgage-backed securities so complicated that the investors couldn’t actually understand them. It’s been true every time a company has made its proxy statements so long, dense and convoluted that none of the stockholders could work out just how much money the CEO was taking home.

And I’d bet dollars to Trump casino IOUs that it’s true when a presidential candidate who boasts about being worth “billions,” and who boasts about giving “millions” and even “tens of millions” to charity, then goes out of his way to hide any evidence.

Whenever people hide financial documents, there’s a reason for it.

Trump claims he will release his returns when a “routine audit” is complete. There is absolutely no logical reason — none — to take that preposterous statement seriously. No “audit” would stop him from releasing his returns. Even the IRS came out and confirmed that. It’s obvious to anyone with even a basic knowledge of tax affairs. Oh, and what about previous years?

Some think Trump is hiding his returns because he’s hiding financial links to the Kremlin or unsavory characters. But those might not show up on his tax returns, unless he was really, really foolish. (I’m not ruling that out.) Others speculate that he’s hiding his minuscule tax bill. But Trump has already boasted about how easy it is for rich guys like him to game the system. That probably wouldn’t stop him from releasing his returns either.

The one thing his tax returns can’t hide, however, is how much or little he gets to deduct for his charitable donations.

And note that the IRS counts only real, bona fide donations. So-called “donations” of time, goodwill or the use of an empty club room in the off-season don’t cut it.

The U.S. media is hamstrung in covering this story by a combination of cowardice and its peculiar version of the Queensberry rules. For example, we keep reporting the defenses and obfuscations offered by the Trump campaign, even though they are completely bogus.

So all praise to David Fahrenthold at the Washington Post. Through some terrific old-school, shoe-leather reporting, he has already done everything reasonable to find charities that have received checks from Donald Trump. The results: not good.

Trump? He has suggested he won’t release his returns before the election, which surely means “ever.” But he does say that as president he will try to “loosen up” the libel laws so he can sue the Washington Post “for a lot of money” for criticizing him. Good to know.

I contacted Trump’s campaign yesterday to ask about the returns. Their response? To borrow a popular twitterism: “crickets.”

The only response that would count for anything would be to release the returns. On that the campaign’s silence is deafening. And unless that changes, we have to draw the only conclusions that make sense.