Tax cuts, especially tax cuts heavily skewed toward the rich, have been a staple of Republican presidential politics since Ronald Reagan. They still are, even in this wackiest of political seasons, although Donald Trump ’s proposal is a moving target.  As recently as the GOP convention, Mr. Trump was still bragging that “I have proposed the largest tax reduction of any candidate who has declared for the presidential race.” But on Monday, that tax plan disappeared from his website, and he sketched a new plan which, his advisers claimed, would cost about one-quarter to one-third as much as his old plan. Really? Stand by for further tweets.  This week’s Trump plan cuts the top income-tax bracket rates to just 33% for personal taxes and 15% for corporate taxes. Not even the Chamber of Commerce seeks a corporate tax rate that low. And just for fun—fun for the super-rich, that is—he’d abolish all estate and gift taxes.  Though details are sorely lacking, Trump II resembles the House Republican plan. But here’s one key difference. The House plan sets the tax rate on pass-through business income at 25%, thereby opening up a modest 8-point tax loophole (33% minus 25%) for wealthy business owners. Trump II makes the corresponding tax gap a whopping 18 points (33% minus 15%), thereby opening up a loophole wide enough to drive the whole Trump Organization through.  Hillary Clinton opposes the Trump plan, of course, both for the revenue losses we can ill afford and because inequality is bad enough already. She proposes, instead, to increase taxes on the rich (incomes over $2 million a year) and the very rich (over $5 million). The Tax Policy Center estimates that her plan would raise about $1.1 trillion over 10 years, which is enough to pay for her proposed programs without blowing a hole in the budget. Nearly all the new revenue comes from the top 1%.  So there’s quite a difference. This aspect of the 2016 tax debate has a familiar ring. Ronald Reagan and Jimmy Carter would recognize it. So would Mitt Romney and Barack Obama.  But a second tax debate is novel. It’s the outcry over Mr. Trump’s imperious refusal to release his tax returns—something no candidate, Republican or Democrat, has done in the last 40 years. In stark contrast, Mrs. Clinton has released her tax returns dating all the way back to 1977. But Mr. Trump won’t budge, telling ABC’s George Stephanopoulos, for example, that his tax rate is “none of your business.”  Well, maybe it’s none of Mr. Stephanopoulos’s business. But it is the public’s business—for a number of good reasons including concerns about Mr. Trump’s alleged Russian connections and letting voters make judgments about actual and potential conflicts of interest. Do Mr. Trump or his business partners owe anything to Russian oligarchs? How much would Mr. Trump and his family save if the Trump tax plan became law?  Here’s about all we know about The Donald ’s tax returns:  • He says he’s under IRS audit for returns since 2009, which he won’t release until the audits are complete. Have you ever waited for a reply from the IRS, even for a relatively simple matter? Can you imagine how complex Mr. Trump’s tax returns must be? Do you think there’s any chance the audits will be complete by Election Day?  • The IRS does not object to anyone releasing his tax information while under audit. To prove the point, Warren Buffett recently offered to do so—if Trump will.  • Audits of Mr. Trump’s returns prior to 2009 are history, yet he also refuses to release those.  • The last Trump tax returns to see the light of day, for 1978 and 1979, show he paid no taxes. They were unearthed by David Cay Johnston, the intrepid Pulitzer-prize-winning journalist, from filings with New Jersey casino regulators. According to a June report in Politico, also based on casino regulatory matters, the same was true of Mr. Trump’s 1991 and 1993 returns. After that, the lights go out.  • The Donald claims to have given away millions to a host of charities. But after strenuous efforts, Washington Post reporter David Fahrenthold could document only one personal charitable donation since 2008—of between $5,000 and $10,000.  All this leaves the impression that Mr. Trump is hiding behind the audit excuse because he doesn’t want voters to know that he pays no income taxes, or that he lies about his charitable donations, or that he’s on the hook to oligarchs tied to Vladimir Putin. Perhaps all three.  These are just guesses, however. They could all be wrong. There is only one way to find out: Mr. Trump, take down that wall.  Mr. Blinder, a professor of economics and public affairs at Princeton University and former vice chairman of the Federal Reserve, is an informal policy adviser to the Hillary Clinton campaign.
Princeton professor Alan S. Blinder writes that Donald Trump refuses to release his tax returns while his new tax plan is a gift to the super-rich.