The Marketplace Fairness Act grants states the authority to compel online and catalog retailers (“remote sellers”), no matter where they are located, to collect sales tax at the time of a transaction – exactly like local retailers are already required to do. However, there is a caveat: States are only granted this authority after they have simplified their sales tax laws.
Simplification is required because of two Supreme Court rulings (Bellas Hess and Quill, described below) cite concern that collecting sales tax for multiple states would be too difficult.
The Marketplace Fairness Act requires that states must simplify their sales tax laws in order to ease those concerns and make multistate sales tax collection easy. Specifically, states seeking collection authority have two options for simplifying their sales tax laws. (Sourced From MFA)
Here is the Bill That Has Been Introduced