Hillary Clinton is undoubtedly correct that Donald Trump is hiding something in refusing to release his tax returns. What might that something be? We can only speculate. Surprisingly, I haven’t seen much speculation in the media, so I am offering herewith my own hunches as to the possible/probable motivations for Trump’s tax return reticence. Listed in ascending order of potential damage to his campaign, here is what he might be hiding:

1. Trump hardly pays income tax—Real estate developers, probably even more than most other moguls, enjoy a variety of tax breaks that enable them to minimize their financial obligations to Uncle Sam. It’s quite possible that there have been many years when Trump has paid near zero in income tax. Some voters would find that rather galling.   Trump, however, would argue that he doesn’t make the rules, he just uses them to get the maximum benefit for himself, and that anyone would be a fool to do otherwise.   A very reasonable argument that most people, but maybe not everyone, would find acceptable.
2. Trump isn’t all that rich—Lacking any experience in government, Trump’s main claim to be qualified for the presidency is his purportedly fabulous success as a businessman. He claims to be worth $10 billion, but no one really believes that. Independent estimates put his wealth in the $3-4.5 billion range, which, given that he started out with a sizable inheritance, would indicate that he has had respectable but not particularly spectacular success in his businesses. But what if he’s worth a lot less even than that? In that case, Trump’s vaunted business success would be revealed to be as fraudulent as Trump the populist.   His tax returns would give us a better fix on just how rich he is.
3. Trump is a selfish miser—This isn’t just speculative. The exhaustive investigations of the Washington Posts’s David Fahrenthold have failed to turn up any charities that have benefitted from Trump’s largesse. It is quite possible that Trump simply doesn’t give, or hardly ever gives, to charity. That wouldn’t look good. Americans expect their billionaires to manifest some kind of social conscience, something indicating a concern for others.   Especially, you would think, one who is running for POTUS.
4. The proverbial iceberg—From what we know about Trump University, we can surmise that Trump is a con artist in business as well as in politics. But we know about Trump University because there is a well-publicized suit against it. Trump’s business empire is composed of numerous privately owned companies about which we know little because they are private. How many other Trump enterprises skirt or cross the line that separates legitimate from ethically and/or legally dubious business? How many innocent, over-trusting people has Trump bilked? The tax returns could provide some clues, opening up paths of investigation that Trump would prefer to block.
5. The Russian connection(s)—Trump has asserted that he has no investments in Russia, but that isn’t the point. His tax returns would help us determine how much the Russians have invested in him. As Josh Marshall and others have pointed out, Trump’s frequently expressed admiration for Vladimir Putin could be rooted in Trump’s business interests. Remarkably, Trumps’s attraction to the current leading boogey man of American foreign policy hasn’t seemed to hurt him much up till now, but black and white documentation of his Russian involvements could change that.

Am I missing anything? Comments, please.