Physician Practice Acquisitions v Isolated Transaction The Stark law provides an important "isolated transaction" exception to the referral prohibition related to compensation arrangements. This exception encompasses, among other things, a one-time sale of a physician's medical practice. The Stark I regulations define an isolated transaction as one that, among other requirements, involves only a single payment for the practice. Although it was hoped that perhaps HCFA would expand that definition to include installment payments, that has not happened. The proposed regulations maintain the single payment requirement. Further, the proposed regulations add an additional requirement that the parties conducting the isolated transaction complete on additional transactions for the next six months.However, even if the "isolated transaction" exception is not met, this does not necessarily mean that the Stark law is violated. Other exceptions may be available. For example, the physician whose practice is purchased may retire, so that he or she no longer engages in referrals. In addition, the compensation arrangement exception or the new personal service arrangement exception might be met. Further, if a hospital is the acquiror, the hospital ownership exception could apply. The preamble indicates that secured debt and even some types of unsecured debt can qualify as an ownership or investment interest in a hospital.