5 Sales Tax Nexus Triggers Every Online Seller Should Know
Sam's List Editorial | 2026-06-27
5 Sales Tax Nexus Triggers Every Online Seller Should Know Sales tax is where a lot of online sellers discover, too late, that they owed tax in states they never set foot in. The concept that decides it is nexus: a connection to a state strong enough to require you to collect and remit its sales tax. Since the 2018 Wayfair decision, that connection can be purely economic. Here are five sales tax nexus triggers every online seller should know, and what each one means for you. Rules vary by state and change frequently, so treat this as a map of what to watch, not a substitute for checking each state's current thresholds with a professional. 1. Economic Nexus: Crossing a Sales Threshold After Wayfair, most states impose economic nexus once your sales into that state exceed a threshold, commonly a dollar amount or a number of transactions in a year. Cross it, and you generally must register, collect, and remit, even with no physical presence. This is the trigger that surprises sellers most. 2. Physical Presence The traditional trigger still applies. An office, employees, a store, or other physical footprint in a state creates nexus. For online sellers this often shows up as a remote employee or contractor in another state. 3. Inventory Stored in a State This one catches Amazon FBA sellers constantly. If a marketplace stores your inventory in a warehouse in a given state, that stored inventory can create physical nexus there, even if you have never been to the state. Knowing where your inventory sits matters. 4. Marketplace Facilitator Rules Many states now require marketplaces like Amazon to collect and remit sales tax on your behalf for sales through their platform. That helps, but it does not always cover your sales on your own website or other channels, and you may still have registration or reporting obligations. Do not assume the marketplace handles everything. 5. Affiliate or Click-Through Connections Some states create nexus through relationships with in-state affiliates or referrers who send you customers. If you run an affiliate program with partners in certain states, that can be a trigger worth checking. What to Do When a Trigger Applies When you suspect nexus in a state, the usual steps are to confirm the current threshold, determine when you crossed it, register if required, and start collecting going forward, while assessing any past liability. Ignoring it does not make it disappear; unpaid sales tax accrues with interest and penalties. This is exactly where an ecommerce specialist earns the fee. ECOM CPA is a Sam's List firm focused on...
