In January, GOP presidential candidate Donald Trump said,  I try and pay as little tax as possible, because I hate what they do with my tax money. I hate the way they spend our money.  Donald has avoided releasing his tax returns to the public and now we know why.In 1987, Donald signed off on a series of accounting changes that allowed his first hotel to shortchange New York City by nearly $3 million in rent.Just 10 years previously, Trump made a deal which would free the hotel of $160 million in property taxes over the course of 40 years. While that sounds good so far, it was also supposed to guarantee the city a small financial stake in its success: New York City received annual rent payments tied to the Grand Hyatt s profits, according to CBS.In 1986, the hotel had its best year, raking in nearly $80 million. City officials expected to receive at least as much as the $3.7 million paid the year before.But that never happened because a month after Trump and his partners signed off on the accounting changes, the city was paid only $667,155.For two years, city auditors were stonewalled each time they tried to address the issue.Experts asked by CBS News to examine the city auditor s report, which was completed in 1989, described the behavior of hotel and Trump Organization officials as  unusual  and  unheard of. Something was fishy there,  Karen Burstein, who was the city s auditor general at the time, said referring to the hotel s owners.  This was not the behavior of an innocent party. I think that s what became evident to us. When a date was eventually agreed upon for an audit, it was cancelled by hotel lawyers in a rare move. It s one of those things you want closure on. Why would you want this hanging over your head?  said Tobey, a partner at Perelson Weiner LLP, which audits corporations, hedge funds, private equity funds and non-profits.  Stonewalling auditors is not a common practice. You want to make them go away. When city auditors finally got a glimpse of the goings on at the hotel, they found missing books and unacceptable accounting principles. Hotel officials tried to keep the audit from being released to the public, much like Donald is doing with his tax returns now.According to Donald, he doesn t remember any of this. I sold the hotel many years ago for a tremendous profit. By building the hotel I created thousands of jobs, saved the Grand Central area, and helped to revive a dying, at the time, New York City,  Trump told CBS.  The city was extremely happy with that development and you re now bringing up something thirty years later that I ve never heard about. Donald may not really want to become President, because really, he s only into self-promotion. He could be looking for a way out of this race. Trump wants to Make Trump Great Again but now that he s in the spotlight, things may not work out well for him since his previous business ventures are becoming public. Donald s self-promotion may be his undoing. It s funny how that works.Photo by Darren Hauck via Getty