The Secretary is authorized to prescribe such regulations as may be necessary or appropriate to determine whether an interest in a corporation is to be treated for purposes of this title as stock or indebtedness (or as in part stock and in part indebtedness).
The characterization (as of the time of issuance) by the issuer as to whether an interest in a corporation is stock or indebtedness shall be binding on such issuer and on all holders of such interest (but shall not be binding on the Secretary).