This article examines current regulatory models, which tend to apply enforcement at the level of “custody” and “control” over financial transactions. However, with the rise of decentralized exchanges, the author asks what might happen to these models if financial transactions take place without custodians. Using the example of the IRS’s definition of “withholding agent,” he examines arguments the IRS might use to require withholding on decentralized exchanges. In response to the rise of decentralized exchanges, the IRS and other agencies could update their regulatory approaches and apply enforcement at the level of “profit” rather than control, using the Controlled Substances Act as a model. However, such an approach might stifle decentralized exchange technology in its infancy.