But the I.R.S. says Mr. Trump is free to release the returns at any time and to defend their accuracy, just as President Richard Nixon did while he was undergoing an audit. In the past, Mr. Trump has not hesitated to attack the I.R.S. as “very unfair,” but now he stands before the voters using the agency as a shield against disclosure.
...The voters deserve to know what Mr. Trump is hiding, particularly considering his history of bankruptcies, the government investigations of Trump University and other dodgy parts of his branded universe. As the campaign rolls toward the fall, pressure will grow on Mr. Trump to be far more transparent than he has been. Responding with another pithy tweet won’t do.
[source : Donald Trump Ducks Tax Disclosure, New York Times, http://www.nytimes.com/2016/08/01/opinion/donald-trump-ducks-tax-disclosure.html?action=click&pgtype=Homepage&clickSource=story-heading&module=opinion-c-col-left-region®ion=opinion-c-col-left-region&WT.nav=opinion-c-col-left-region, 1st August 2016]
I think there could be something more sinister behind Trump's refusal to release his tax returns. His relationship with Roy Cohn and hs purchase of CIA/mob money-laundering front Resorts International stink of CIA.
But along with his tax returns he should also make public:
1. his mental health records;
2. details of the supply chains of himself and his daughter Ivanka, and the plans the have made to ensure that their supply chains are 100% made in 'Murica.