There is no requirement that a person running for public office has to make their income tax returns public. Presidential candidates must file financial disclosure records, which describe their income and assets, but financial disclosure records do not reveal how much a person paid in taxes. According to The Washington Post, Trump’s tax information from the late 1970s was made public in 1981, and revealed that at the time, he had taken advantage of tax loopholes paid no taxes whatsoever.
While Trump is not breaking any laws by refusing to make his tax returns public, he is bucking a long precedent set by former presidential candidates who have voluntarily released their returns. He may also be compromising his appeal to working-class voters, who could conclude that because he refuses to release his returns, that Trump has something to hide.