Prohibits a state from imposing any tax on electronic commerce (i.e., transactions conducted over the Internet or through Internet access) of any person unless that person has a physical presence in the state during the period to which such tax applies or is incorporated or domiciled in such state. Sets forth criteria for determining physical presence, including: (1) being physically in a state or assigning one or more employees to a state; (2) using the services of an agent to establish or maintain the electronic commerce in the state; or (3) leasing or owning tangible personal or real property in the state. Exempts from the definition of "physical presence" entering into an agreement to share revenue generated by the electronic commerce of another person, presence in the state for less than 15 days in a taxable year, and presence in a state to conduct limited or transient business activity.