f 26 U.S.C. 17201 does not occur until the defendant commits an affirmative act constituting an evasion or attempted evasion of the tax). 13. See United &WM v. Bishop, 412 US. 346. 357-58, 93 S-Ct. 2008, 2016. 36 1...F.d.2d 941 (1973). 1980 did not apply to these crimes, because they did not occur unt