By now, the impact of the Supreme Court of the United States South Dakota v. Wayfair, Inc. decision is widely known. Imposing sales tax obligations on out-of-state businesses is old news and the new norm. But even though most states have already issued their new rules, sellers across the U.S. still have their work cut out for them: Figuring out their liabilities and rebuilding their tax strategies for states they never accounted for is no small feat.

States have always been fiercely independent when it comes to their laws and sales tax is no exception. Here’s a look at what made headlines in 2019 and what to expect in the coming year.