After the U.S. Supreme Court’s ruling last week in South Dakota v. Wayfair, one big question—whether the court will overturn Quill v. North Dakota—has an answer. But the related question of what sales tax structure online retailers will face going forward is still unresolved.

In a much-anticipated opinion, the Supreme Court ruled 5-4 on Thursday that states are allowed to collect sales taxes from online retailers that don’t have a physical presence within their borders. This overturned the court’s 1992 decision in Quill, which had affirmed the “physical presence” test for state sales-and-use tax collections.