A wholesale license (also called a resale certificate) is required in almost all states where an individual or business engages in the commercial activity of buying goods for the purpose of resale. Most online suppliers will ask for a wholesale license to be provided from a state where you or your business has physical presence. This is done so the supplier alleviates themselves of the responsibility of having to collect sales tax on the goods they sell you because you will have the responsibility of collecting the sales tax when those goods are sold.