5 Sales Tax Nexus Triggers Every Online Seller Should Know

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 ecommerce sellers, including the multistate sales tax mess that comes with selling everywhere at once. A specialist can map your nexus footprint and sort out registration and exposure. Confirm credentials and fit before engaging.

Review ECOM CPA's profile on Sam's List.

Frequently Asked Questions

What is sales tax nexus? Nexus is a connection between your business and a state strong enough to require you to collect and remit that state's sales tax. It can come from physical presence, like inventory or employees, or from economic activity, like exceeding a state's sales threshold after the 2018 Wayfair decision.

Does Amazon collecting sales tax mean I'm covered? Not necessarily. Marketplace facilitator laws require platforms like Amazon to collect on sales made through them, but that may not cover sales on your own website or other channels, and you may still have registration or reporting duties. Confirm your full obligations rather than assuming.

Can storing inventory in a state create nexus? Yes. Inventory stored in a state, including in a marketplace fulfillment warehouse, can create physical nexus there even if you have never visited. FBA sellers in particular should know which states hold their inventory.

How do I know if I owe sales tax in a state? Check each state's current economic nexus threshold against your sales and transactions there, and review any physical connections like inventory or employees. Because thresholds and rules change, many sellers use a specialist to map their footprint and stay compliant.