26 U.S.C. § 6020 : US Code - Section 6020: Returns prepared for or executed by Secretary

    (a) Preparation of return by Secretary
      If any person shall fail to make a return required by this title
    or by regulations prescribed thereunder, but shall consent to
    disclose all information necessary for the preparation thereof,
    then, and in that case, the Secretary may prepare such return,
    which, being signed by such person, may be received by the
    Secretary as the return of such person.
    (b) Execution of return by Secretary
      (1) Authority of Secretary to execute return
        If any person fails to make any return required by any internal
      revenue law or regulation made thereunder at the time prescribed
      therefor, or makes, willfully or otherwise, a false or fraudulent
      return, the Secretary shall make such return from his own
      knowledge and from such information as he can obtain through
      testimony or otherwise.
      (2) Status of returns
        Any return so made and subscribed by the Secretary shall be
      prima facie good and sufficient for all legal purposes.