New York (CNNMoney) - The Senate approved a long-anticipated Internet sales tax proposal on Monday, moving the legislation one step closer to enactment and paving the way for shoppers to pay sales tax on the majority of online purchases.

The so-called Marketplace Fairness Act would allow the 45 states (and the District of Columbia) that currently charge sales taxes to require large online retailers to collect tax on purchases made by their residents. The law would only apply to online sellers that have sales of at least $1 million in states where they don't have physical operations, like a store or a warehouse.