Stop Taxing Our Potential Act of 2018 This bill prohibits a state from imposing on a person obligations related to collecting or paying a sales tax, use tax, or similar tax unless the person had a physical presence in the state during the calendar quarter with respect to which the obligation is imposed. A person is physically present if the person's business activities in the state include: maintaining a commercial or legal domicile in the state; owning, holding, leasing, or maintaining certain property in the state; having one or more employees, agents, or independent contractors in the state who provide on-site design, installation, or repair services on behalf of the remote seller; having one or more employees, exclusive agents or exclusive independent contractors present in the state who engage in activities that substantially assist the person to establish or maintain a market in the state; or maintaining an office in the state at which three or more employees are regularly employed. The bill specifies certain activities and agreements that indicate a de minimis physical presence that is excluded from the definition of "physical presence." The bill also specifies that U.S. district courts have original jurisdiction over civil actions to enforce this bill.