If U.S. sales tax feels chaotic, you are not alone. For non-US founders, the system is fragmented, state-driven, and often poorly explained. This page exists to give you orientation before diving into detail.
U.S. sales tax is not a single national system. Each state controls its own tax rules, thresholds, and definitions of what is taxable.
The two ways nexus is created
Physical nexus arises when your business has people or property in a state.
Economic nexus arises when your sales activity exceeds a state's threshold.
Most businesses only trigger nexus in a small number of states.
Ecommerce vs SaaS exposure
Ecommerce brands often create nexus through inventory and fulfilment networks. The ecommerce sales tax guide separates that physical-presence question from economic thresholds and marketplace sales. SaaS companies more commonly trigger nexus through revenue thresholds, and then face a second question of whether the state taxes SaaS at all (see sales tax for SaaS companies).
When founders should act
Sales tax problems rarely arise from growth itself. They arise from discovering obligations too late. Early clarity usually prevents expensive clean-ups.
Next step: Check your nexus status with our free Nexus Checker tool.