South Dakota has settled the Wayfair case. The landmark Supreme Court decision in South Dakota v. Wayfair began as a challenge by several companies to the state's economic nexus law. That law says out-of-state sellers without a physical presence in the state must collect sales and use tax when they make a certain amount of sales into the state (i.e., $100,000 or 200 or more separate transactions).
The United States Supreme Court held the law was constitutional, and it remanded the case to the South Dakota State Circuit Court for procedural purposes. The state case has reached a settlement agreement that requires the parties to the lawsuit to collect sales and use tax in South Dakota beginning January 1, 2019. The parties to the lawsuit were Wayfair, Overstock, and Newegg. Other remote sellers became subject to the economic nexus law on November 1, 2018.