The question I address here, albeit lightly, is whether, if it is shown that any President committed tax fraud (covering both evasion and tax perjury), the tax fraud would be an impeachable offense. I do not address the issue of whether he can be indicted for tax fraud or any other offense while he still serves as President (although I do have an aside on that at the end).
The only actual example was President Nixon. As I note in my chapter on Criminal Penalties and the Investigative Function, Chapter 12 in Michael Saltzman and Leslie Book, IRS Practice and Procedure (Thomsen Reuters 2015), ¶12.01. Criminal Penalties in General, ¶ 12.01[1] In General at fn. 6: Richard Nixon's alleged tax crime was fully pardoned in a general pardon by President Ford who succeeded Nixon on his resignation, but as to impeachment:
Among President Nixon's alleged crimes was tax evasion, which the House Judiciary Committee declined to include in the articles of impeachment because, it believed, tax evasion was not an impeachable offense. Mezvinsky & Freedman, Federal Income Tax Evasion as an Impeachable Offense, 63 Geo. L.J. 1071 (1974-1975).But, there is authority from a scholar that income tax fraud can be an impeachable offense. See Charles L. Black, Impeachment: A Handbook (1974), with pertinent portions republished by permission in Charles L. Black, The Impeachable Offense (Lawfare 7/20/17), here:
Income-Tax Fraud
Serious income-tax fraud by a president, particularly when the vehicle of such fraud is a set of papers resulting from his holding one government office, and when he might anticipate virtual immunity from serious audit because of his occupying the presidency, would seem definitely impeachable, in addition to being criminal. The offense seems akin to bribery, in that it uses office for corrupt gain; in any case, it undermines government, and confidence in government. A large-scale tax cheat is not a viable chief magistrate.
