Digital Goods and Services Tax Fairness Act of 2018 This bill prohibits a state or local jurisdiction from imposing: (1) multiple taxes on the sale of a covered electronic good or service, or (2) discriminatory taxes on the sale or use of a digital good or service. A "digital good or service" is delivered or transferred electronically to a customer. A "covered electronic good or service" is a digital good, digital service, audio or video programming service, or Voice over Internet Protocol (VoIP) service. The bill also: specifies services that are excluded from the definition of "digital service;" restricts taxation of a covered electronic good or service to taxation by a state or local jurisdiction whose territorial limits encompass a customer tax address, as defined by this bill; makes the seller of covered electronic goods or services responsible for obtaining and maintaining such address; and specifies rules regarding the taxation of bundled transactions, digital code, and VoIP services.