Economic nexus is the rule that lets a state tax you based on how much you sell into it, not whether you have ever set foot there.
Economic nexus is a connection to a state, created purely by economic activity, that obligates a seller to collect and remit that state's sales tax. The connection is measured by a threshold, usually a dollar amount of sales, a number of transactions, or both, into that state over a defined period. Once a seller crosses the threshold, the obligation begins, even with zero physical presence in the state.
The concept replaced the older rule that a state could only tax sellers with a physical foothold there. Today, an ecommerce brand in one state can owe sales tax in dozens of others solely because of where its customers live and how much they buy.
Before 2018, a state could only require a business to collect its sales tax if the business had physical presence there: an office, employees, or inventory. That standard, set by earlier Supreme Court cases, left remote and online sellers largely outside state sales tax systems.
In South Dakota v. Wayfair, Inc. (2018), the Supreme Court overturned the physical-presence requirement. It upheld South Dakota's law taxing out-of-state sellers that exceeded $100,000 in sales or 200 transactions into the state. Within a couple of years, nearly every state with a sales tax enacted its own economic nexus law modeled on that decision.
A threshold has three parts: a measure, a number, and a period.
A seller crosses economic nexus the moment its activity into a state exceeds that state's number over that state's period. From that point, the seller must register, collect tax on taxable sales, and file returns there.
| ELEMENT | COMMON VALUE | WHY IT VARIES |
| Sales measure | $100,000 | Some states use $250,000 or $500,000 |
| Transaction measure | 200 transactions | Many states have dropped this prong |
| Connector | "OR" (either triggers) | A few use "AND" or sales only |
| Period | Current or prior calendar year | Some use a rolling 12-month window |
Because the parts differ by state and change over time, any specific threshold should be treated as verify-current before relying on it.
These are two separate ways to acquire a sales tax obligation, and a seller can have both in the same state.
If either applies in a state, the obligation exists. A seller does not need both.
Economic nexus determines whether you have an obligation in a state. It does not always determine who pays. Marketplace facilitator laws require platforms like Amazon, Walmart, eBay, and TikTok Shop to collect and remit sales tax on the sales they facilitate.
So a seller can have economic nexus in a state, yet have the tax on its marketplace sales handled entirely by the marketplace. The seller's own direct sales (through Shopify or its own site) into that state remain the seller's responsibility. Some states also count marketplace sales toward the economic nexus threshold even though the marketplace remits the tax, which can push a seller over the line for its own-channel obligations.
Crossing economic nexus quietly is the expensive part. The obligation starts on the trigger date, not the date you notice. Unremitted self-collected tax accrues with interest, and the tax you collect from customers is money held in trust for the state, not revenue.
Accurate books separate three things per state: whether nexus exists, marketplace-facilitated tax already remitted by the platform, and self-collected tax you owe. ConnectBooks pulls settlement data from Amazon, Shopify, Walmart, eBay, and TikTok Shop and separates marketplace-facilitator tax from self-collected tax automatically, so your liability reflects only what you actually owe. Plans start at $149/mo.
For the practical, state-by-state walkthrough, see /blog-posts/ecommerce-sales-tax-nexus-primer-2026.
| NEXT STEPTrack economic nexus and separate the tax you owe from what the marketplace already remitted, automatically. See /pricing. |
It is the point at which your sales into a state are large enough that the state can require you to collect and remit its sales tax, even though you have no office, employees, or inventory there. The trigger is a threshold, often $100,000 in sales or 200 transactions, measured over the current or prior year.
No. Physical nexus comes from a tangible presence such as inventory, staff, or an office in the state. Economic nexus comes from sales volume alone. You can have one, the other, or both. If either applies in a state, you have a sales tax obligation there.
In some states, yes, but many have removed it since 2019 and rely on a dollar threshold only. Where it still applies, a high-volume seller of low-priced items can cross nexus on transaction count well before hitting the dollar figure. Always check the current rule for the specific state.
You can. Economic nexus describes whether you have an obligation in the state; marketplace facilitator laws decide who remits the tax on marketplace sales. Amazon handling your Amazon tax does not erase nexus, and your direct-channel sales into that state may still be yours to collect and remit.
On the date you cross it, under that state's rules, not when you register or first notice. That is why unmonitored thresholds are risky: the liability and any interest accrue from the trigger date forward, regardless of when you act on it.
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