“I already paid the tariff — why is there another tax called sales tax?” The most common double-take among Taiwanese sellers entering the US. The answer is simple: two entirely different taxes — customs duty is federal, collected at the border (how it computes); sales tax is state, collected when the sale happens. Neither excuses the other. And whether sales tax reaches you turns on one word: nexus.
The foundation: sales tax is a state tax
There is no federal sales tax. Rates, taxable scopes and filing schedules are set state by state (sometimes county and city on top): some states run high rates, some none at all, and the same product can be taxable in state A and exempt in state B. So “what is the US sales tax rate” is the wrong question — the right one is “in which states do I owe, and what does each charge.”
Nexus: your connection to a state
A state can tax you only if you have sufficient connection to it — the legal concept called nexus, triggered two ways:
- Physical nexus: presence in the state — an office, employees, sales reps, or the one everyone forgets: inventory. Goods sitting in that state’s 3PL or Amazon FBA warehouse establish physical nexus, even with you and your company entirely in Taiwan
- Economic nexus: since the 2018 Wayfair decision, no person or goods needed — cross the state’s annual sales or transaction threshold and the obligation switches on. Thresholds differ by state and get amended; current state rules govern, and this article deliberately lists no numbers
Nexus once triggered brings a full kit: register with the state, collect from its buyers, file and remit on schedule — not a one-off payment. Worse, the obligation runs from the day you crossed the threshold, not the day you noticed; when a state comes back, tax, interest and penalties arrive together.
Two mercies
- Marketplace facilitator laws: on Amazon-class platforms, most states now make the platform collect and remit — shrinking the seller’s direct burden. But it covers platform orders only; your own website’s orders remain yours
- The B2B resale certificate: sales tax hits final consumers only. Selling to US distributors and importers who resell, against a valid resale certificate, is exempt — the normal state of most B2B export transactions. Your duty is collecting and keeping the certificates; accept a fake or expired one and the liability can walk back to you
One adjacent unmix: the W-8 form your customer’s onboarding demands belongs to income-tax withholding — a different line entirely from sales tax (the tax-forms article).
Logistics placement is tax placement
Once nexus clicks, the operational insight follows: where the goods sit, the tax follows. Whether to use a US warehouse, in which state, how inventory spreads — never just freight-and-speed questions; they are sales-tax switches. SKYCARGO INC’s import-export and warehousing services run Taiwan-US B2B placement daily; tell us the products and sales model for the logistics-side view, and take the tax side to your accountant. (Personal shipments: Shiptw.)
General information only, not tax advice; state nexus thresholds and rules change frequently — consult your accountant under each state’s current law.
