What is US sales tax nexus for international sellers?

Nexus is the connection triggering sales tax obligations in a US state. For international sellers, it's established through physical presence (warehouse, inventory) or economic nexus (typically $100,000 in sales or 200 transactions per state). Once triggered, you must register, collect, and remit sales tax. Swap's automated compliance covers all 50 states, manage US sales tax in just 15 minutes a month.