Sales tax nexus is the connection between a business and a taxing jurisdiction that is strong enough to require the business to collect and remit sales tax there. It can come from physical presence, such as an office, employees, or stored inventory, or from economic activity that crosses a set sales or transaction threshold. Once you have nexus in a state, you are responsible for registering, charging the correct rate, and filing returns there.
How it works
Nexus is decided state by state, so a single business can owe sales tax in some places and not others. Physical nexus is triggered by a tangible footprint, including remote employees or goods held in a third party warehouse. Economic nexus, which most US states adopted after the 2018 South Dakota v. Wayfair decision, is triggered when your sales into a state pass a threshold. A common example is 100,000 dollars in sales or 200 separate transactions in a year, though the exact numbers vary.
Why it matters
If you have nexus and fail to collect, the liability usually falls on you, not the buyer, plus penalties and interest. Growing merchants often cross economic thresholds without noticing, especially once they sell across many states.
How it applies to B2B quoting on Shopify
Nexus still governs quotes, not just standard checkout. A quote may be tax exempt if the buyer is a reseller with a valid exemption certificate, but only where you have nexus and have collected that certificate. Because a Live Quote converts to a real Shopify draft order and the buyer pays through native Shopify checkout, tax is calculated by your Shopify tax settings at acceptance. Keep those settings accurate for every state where you have nexus. See the B2B quoting glossary for related terms.