even without adding in additional B2B sales. First, the Census Bureau’s retail e-commerce data include sales by motor vehicle and parts dealers, which comprise 19 percent ($24 billion in 2007) of total retail e-commerce.
Including these sales in the total likely overstates the potential tax base both because automobile sales – regardless of how they are conducted – are subject to taxation at the time of registration, and because many sales of automobile parts are likely B2B sales which are not subject to sales or use taxes in the first instance.