Releasing one’s tax returns was, until this year at least, an established practice for presidential candidates.
Trump essentially admitted that in 2014, when he told an Irish television show, “If I decide to run for office, I’ll produce my tax returns, absolutely.”
The issue also came up when Trump started his infamous “birther” campaign against President Barack Obama, alleging falsely that Obama was born in Kenya and demanding that he release a birth certificate.
“Maybe I’m going to do the tax returns when Obama does his birth certificate,” Trump told ABC’s George Stephanopoulos in 2011.
And when the GOP’s last presidential nominee, Mitt Romney, hesitated to release his returns in 2012, Trump pressured him to disclose — and then praised him for doing so.
http://www.huffingtonpost.com/entry/donald-trump-tax-returns_us_5733b130e4b077d4d6f21a20