In South Dakota v Wayfair Inc., the US Supreme Court has overturned the rule in Quill that a taxpayer must have a physical presence in a state for its activities to have the sufficient ‘substantial nexus’ necessary for it to be required to collect and remit sales and use taxes. The ruling is, of course, important for US state tax and could have far-reaching ramifications for out-of-state entities (both US and international) carrying on business in the US. More intriguingly, the Wayfair case addresses one of the core challenges faced in international tax – realigning taxation with economic substance and value creation in the age of digitalisation.