Corporate tax shelters proliferated during the 1990s, exploiting the flexible partnership tax rules of Subchapter K to defer or eliminate tax on hundreds of billions of dollars of corporate income. The corporate tax shelters were typically structured as a financing transaction in which a U.S. corporation leased its own assets back from a partnership, generating a stream of deductible business expenses while shifting taxable income to a tax-indifferent party such as a foreign bank. Since the transaction allowed the U.S. corporation to raise capital in a tax-advantaged manner in connection with its regular business operations, it was assumed that the transaction had economic substance. Nevertheless, in scrutinizing these shelters, courts have invoked a sham partnership doctrine, derived from the longstanding Culbertson intent test, which disregards a partnership that lacks a bona fide purpose (or, alternatively, a purported partner whose interest does not constitute a bona fide equity participation). This Article examines the structure of a tax shelter that purportedly allowed U.S. corporations (including Dow Chemical and General Electric) to deduct rental and royalty payments for the use of assets contributed to a partnership, while permanently exempting from taxation a circular flow of income to and from the partnership. The Article traces the evolution of the bona fide intent test that several courts have recently applied, independently of the economic substance doctrine, to recast similar transactions involving illusory partnership interests. The Article also argues that the partnership anti-abuse rule continues to play a significant role as a backstop to the judicial anti-abuse doctrines.