The Marketplace Fairness Act gives states the power to compel retailers outside their borders to collect sales tax on online sales that are delivered to the state. Currently, states can only require merchants with a physical presence (nexus) within their borders to collect; this standard was set in the Supreme Court case Quill v. North Dakota in 1992. If the Act passes, more companies would be required to register and collect sales tax, which in turn will help states that need more sales tax revenue.
Read some of the highlights of the Marketplace Fairness Act here.
For further reading, see how Lenovo used a hybrid approach to streamline its tax and auditing process.