The collection of use tax on interstate mail-order and Internet sales is a long-standing tax policy issue. Purchasers rarely pay use tax, and current constitutional doctrine prevents a state from requiring use tax collection by sellers without a physical presence in the state. In the last few years, some states have adopted laws that aggressively test the constitutional restrictions, and support has increased for proposed federal legislation to ease those restrictions. In this article, I argue that the time has come for Congress to authorize states to require use tax collection by out-of-state sellers.