In June, 2018, cross-border tax experts issued their first warnings that a then-just-passed U.S. Supreme Court ruling, in a case known as South Dakota v. Wayfair, would have far-reaching effects on e-commerce businesses that sold their products across U.S. state borders – including those selling into the U.S. from abroad.

As predicted, the decision has left many business owners around the world scratching their heads – and seeking advice.