Economic nexus is a connection to a US state created by sales volume rather than physical presence, which can require you to register for and collect that state's sales tax. Thresholds are set per state - commonly $100,000 of sales into it, and $500,000 in some larger states - and are measured on sales into that state alone.
Why does Economic nexus matter for founders?
You can owe sales-tax obligations in states you have never visited. Thresholds apply per state rather than to total revenue, and marketplace-facilitator rules can shift who collects, so growing ecommerce sellers should monitor state-by-state rather than assume a single national rule.
Where can I read more about Economic nexus?
Note: A plain-English definition for orientation, not legal or tax advice. Rules change - last checked 2026-07-21.