Economic nexus for Shopify sellers: a plain-English checklist

Economic nexus is the reason a Shopify store can owe sales tax in a state it has never set foot in. If you want the why behind the rule, start with our explainer of how economic nexus works. This is the companion piece: a practical checklist to figure out where you actually stand — without a single scary number.

Quick grounding: since the Supreme Court's 2018 decision in South Dakota v. Wayfair, states can require out-of-state sellers to collect sales tax based purely on their economic activity in the state — no physical presence required. Nearly every state with a sales tax has since set its own rules. The catch is that those rules are not uniform, which is exactly why a checklist beats a rule of thumb.

Step 1 — Know what can trigger an evaluation

Two broad categories can create a sales-tax obligation in a state. Check whether either applies to you, state by state.

Economic thresholds

Most states set a threshold based on your activity into that state. The structure varies:

• A revenue threshold — sales into the state above a set amount.
• A transaction-count threshold — a number of separate orders into the state.
• AND vs. OR logic — some states apply revenue or transaction count (either one trips it); others require both; a growing number use revenue only. The logic itself differs by state, so meeting "the number" in one state tells you nothing about the next.

The specific figures are set by each state and change over time — which is why we don't print them here, and why guessing from memory is risky.

Physical presence (still counts)

Wayfair added the economic test; it didn't remove the old one. Physical presence still creates nexus, and for online sellers it shows up in non-obvious ways:

• Inventory stored in a state — including stock sitting in a third-party (3PL) or marketplace fulfillment warehouse. If your goods rest in a state's warehouse, that can be physical presence even if you've never been there.
• An office, employees, or contractors in a state.
• Traveling to sell — pop-ups, trade shows, or markets.

Step 2 — Track the right things, per state

Nexus is evaluated state by state, so a single national sales number won't answer the question. For each state you sell into, keep a running view of:

• Sales revenue into that state over the state's measurement period.
• Order (transaction) count into that state over the same period.
• Where your inventory physically sits (your own space plus every 3PL/fulfillment location).
• Any people or property you have in the state (staff, contractors, equipment).
• In-person selling activity — events, pop-ups, trade shows.
• Which sales flowed through a marketplace vs. your own Shopify checkout (this matters — see the myths below).

The measurement window itself varies by state (some look at the current year, some the prior year), so "track it continuously" is safer than checking once a year.

Step 3 — Don't fall for the common myths

Myth: "All my sales go through a marketplace, so I'm fine."

Marketplace facilitator laws generally shift the collection duty to the marketplace for sales made on it — helpful, but not a blanket exemption. Your own Shopify store sales are still yours to evaluate, some states still expect marketplace sales to count toward your threshold math or expect a registration/return even when the marketplace collects, and mixed channels get complicated fast. "Marketplace-only" is not an automatic pass.

Myth: "I'm under the line everywhere, so I'm safe."

Maybe — but be careful how you know that. Sellers who assume they're comfortably under every state's threshold are often estimating against a single remembered number that (a) differs by state, (b) may use AND/OR logic they're not applying, (c) may count transactions, not just dollars, and (d) may have changed. Physical presence from inventory can also create nexus with no threshold at all. "Probably under" is a feeling; a state-by-state view is an answer.

Myth: "Nexus means I owe back taxes automatically."

Crossing a threshold generally creates a forward-looking obligation to register and collect — not an instant retroactive bill. But ignoring it after you've crossed is where real exposure builds. Catching it early is the whole point of tracking.

Step 4 — Know when to bring in a professional

A checklist tells you where to look; a professional tells you what to do. Consider talking to a sales-tax specialist or CPA when:

• Your tracking shows you're approaching or past a threshold in one or more states.
• You store inventory in multiple states (3PL or otherwise).
• You sell across your own store and marketplaces and can't cleanly separate the channels.
• You think you may have already crossed a threshold in a prior period.

The bigger picture: monitoring, not a once-a-year panic

Economic nexus isn't a one-time test — it's a moving target across up to 50 different rulebooks, re-triggered every time your sales mix or fulfillment footprint shifts. Checking manually once a year is how sellers get surprised.

That's the gap Profenor was built to close. It watches your sales and where your activity lands across all 50 states and flags when you're approaching a state's threshold — so the conversation with your CPA happens early, on purpose, instead of after a notice arrives. (Informational monitoring, not tax advice.)

This article is educational and is not tax, accounting, or legal advice. Economic nexus rules follow South Dakota v. Wayfair, Inc. (2018) and each state's own statutes, which vary and change; no specific thresholds or state figures are stated here by design. Verify your obligations with a qualified sales-tax professional. Profenor is bookkeeping software, not a CPA firm. © Profenor (RJ-DCF LLC).