What is Trump hiding in his tax returns?

Running for president is the longest, toughest job interview in the world. That’s why all serious candidates release information about their health, through notes from their physicians, and about their finances, through releasing their tax returns.

When I ran for president in 2004, I released my tax returns to the public. So did John Kerry, George W. Bush, Barack Obama, John McCain and Mitt Romney. Hillary Clinton has released an astonishing 33 years of her tax returns, the last eight of which are all available on her website.

In fact, since 1976, every major party’s nominee has released his or her tax returns, because that’s what the American people expect of their prospective leaders.

Unsurprisingly, Donald Trump thinks the rules don’t apply to him. He vacillates between stalling the release of his returns and rejecting it outright. His most common excuse is that he cannot release the returns because he’s in the midst of an audit.

There are several problems with his explanations:

The IRS has stated that nothing is preventing him from releasing them. Even Richard Nixon released his returns under an audit.

Trump himself has released his returns in the middle of an audit before. In Pennsylvania and New Jersey, he handed them over to state authorities to obtain gambling licenses. The American people should matter to Trump as much as his casinos did.

What’s stopping him from releasing all the years of returns that are not being audited?

His own campaign admits that Trump has something to hide. Anthony Scaramucci, a hedge fund manager and a member of Trump’s national finance committee, has acknowledged that Trump is afraid of what opposition researchers might uncover.

Perhaps Trump isn’t worth what he says he is. Despite claiming to be worth more than $10 billion, experts have noted that he appears to make less income than they’d expect. In one case, he described his income as including $4.3 million in “golf-related revenue” from a course he owns in Scotland, but the course lost money that year.

Perhaps Trump isn’t paying what he should. Some tax experts suspect he might have used loopholes to avoid paying his fair share. There’s a good chance that Trump is paying a lower tax rate than struggling middle-class families.

Perhaps he’s afraid of revealing his charitable donations — or lack thereof. The causes that people decide to support often reveal much about their values. Trump has told the Associated Press that he does most of his philanthropy in his own name. Releasing his returns would show whether that’s really the case.

Trump shouldn’t be treated differently than every other nominee of the past four decades. His refusal to release his tax returns raises fundamental questions about his business career, his ethics and his ability to tell the truth.

Howard Dean is a former governor of Vermont. He sought the Democratic presidential nomination in 2004 and has endorsed Hillary Clinton in 2016.