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President Trump has repeatedly refused to release his tax returns, falsely claiming that he can't do so because he is under audit. Trump can expect a minimum of four more years of audits, though, because the president and vice president are automatically audited every single year.

The "mandatory examination" has been in place since Watergate, when President Richard Nixon and Vice President Spiro Agnew's tax controversies came to the surface. The IRS decided afterward to make the audits a guarantee for all presidents and vice presidents, regardless of party, so the agency would not appear to have a partisan favor.

The guidelines for auditing the executive branch are extremely detailed, down to even specifying the color of the folder the president's returns must be filed in (orange). Only specific people are allowed to see the returns, and the files are always kept locked away in a cabinet unless the appointed examiner is present.

The audits of President Trump and Vice President Pence will be kept confidential, unless the agency discovers evidence of a tax crime and decides to prosecute. And "of course, there's no telling how rigorous the audits are," CNN Money adds.