Lack of commercial substance: arrangements with round trip financing or accommodating parties fail to reflect genuine economic effect. Section 97 deems an arrangement to lack commercial substance if its substance or effect differs significantly from its form, or if it involves round trip financing, an accommodating party, offsetting elements, or transactions disguising the value, location, source, ownership or control of funds; it also covers arrangements locating assets or residence without substantial commercial purpose other than obtaining a tax benefit. Round trip financing is defined to include series of transfers among parties lacking substantial commercial purpose other than tax benefit, irrespective of traceability, timing, sequence, or mode of transfer, and an accommodating party is one whose main purpose is to obtain a tax benefit for the assessee.