The Supreme Court initially ruled that states could not force online retailers to collect taxes unless they had a physical presence in the state (e.g., a warehouse), but that decision is being revisited. One of the major complaints is that the current law puts brick-and-mortar stores at a major disadvantage. State and local governments could have collected up to $13 billion more in 2017 if they’d been allowed to require sales tax payments from online merchants and other remote sellers, according to a report from the Government Accountability Office, Congress’s nonpartisan audit and research agency. Other estimates are even higher. All but five states impose sales taxes.