What Is Sales Tax Nexus? Every Type Explained (2026)

Nexus in one sentence, and the two questions it answers

Nexus is a relationship, not a rate. It answers one question — can this state make me collect its sales tax? — and, immediately after, a second one that matters just as much: from what date? Everything else in sales tax compliance sits downstream of those two answers. Which rate you charge, what you file, when you file it and how large a back assessment can grow all depend on whether nexus existed and when it began.

A point that gets lost: nexus does not decide who owes the tax. In a normal sales tax state the buyer owes the tax on a taxable purchase either way, and if the seller does not collect it the buyer is supposed to self-assess use tax at the same rate. Nexus decides whether the seller is conscripted as the collector — a trustee holding the state's money between the sale and the return. That framing explains a lot of otherwise strange results, including why a state can reach a business that has never set foot in it.

This guide is the concept. It deliberately contains no state-by-state threshold table, because that already exists and stays current in the economic nexus guide, and because the numbers are the least interesting part of the subject. If you want the arithmetic run for you, the economic nexus calculator takes your sales by state and returns where you stand.

Nexus is evaluated separately for every state, for every tax, and as of every date. There is no national registration and no national threshold. In the five states with no statewide sales tax there is no state-level nexus question at all — you can see which on the sales tax by state page — although Alaska's municipalities have built a nexus regime of their own, which is covered further down.

Where the rule comes from: Bellas Hess, Quill and Wayfair

Two clauses of the US Constitution limit how far a state may reach. The Due Process Clause asks whether there is some definite link, some minimum connection, between the state and the person or transaction it wants to tax. The Commerce Clause asks something related but distinct: whether a state tax burdens interstate commerce. Under Complete Auto Transit, Inc. v. Brady, a state tax survives Commerce Clause review if it applies to an activity with a substantial nexus with the taxing state, is fairly apportioned, does not discriminate against interstate commerce, and is fairly related to the services the state provides¹. Sales tax nexus is a fight about the first of those four prongs, and only the first.

Sources: South Dakota v. Wayfair¹; GAO-18-114²; GAO-23-105359³; Streamlined Sales Tax Governing Board⁷.

1967 and 1992: the mail-order rule

In National Bellas Hess the Supreme Court held that a seller whose only connection with customers in a state is by common carrier or mail lacked the contacts the Constitution required, so the state could not make it collect. In Quill Corp. v. North Dakota in 1992 the Court overruled the due process half of that holding — a business does not need to be physically present to satisfy due process — but kept the physical presence rule alive under the Commerce Clause, grounding it in the substantial nexus prong¹. For twenty-six years, that was the answer: no people, property or agents in the state, no collection duty.

2018: the rule breaks

South Dakota wrote a law to test it. Sellers with more than $100,000 of goods or services delivered into the state, or 200 or more separate transactions for delivery into the state, had to collect as if physically present. The state was blunt about why: with no state income tax, sales and use taxes account for over 60 percent of its general fund, and it estimated annual losses of $48 to $58 million from uncollected remote tax¹. Nationally, the Government Accountability Office put the figure at roughly $8 billion to $13 billion in 2017, about 2 to 4 percent of all state and local general sales tax revenue².

On June 21, 2018 the Court held that the physical presence rule of Quill was "unsound and incorrect" and overruled both cases. The replacement standard is a quotation worth keeping: substantial nexus "is established when the taxpayer [or collector] avails itself of the substantial privilege of carrying on business in that jurisdiction"¹.

The Court's reasoning was aimed squarely at the arbitrariness of the old line. It set out two online furniture sellers: one keeps a few items in a small warehouse in North Sioux City, South Dakota and must collect on everything it sells into the state; the other runs a major warehouse just over the border in Nebraska and a website with a virtual showroom reachable from every home in South Dakota, and under Quill owed nothing. The Court called the physical presence rule artificial not merely at its edges but "in its entirety", and noted that states had already been driven to absurd workarounds — Massachusetts had proposed treating cookies on residents' browsers and downloaded apps as physical presence¹.

What Wayfair did not settle

The Court did not bless every possible state law. It pointed to three features of South Dakota's statute that appeared designed to prevent undue burdens on interstate commerce: a safe harbor for sellers transacting only limited business, a bar on retroactive application, and South Dakota's membership of the Streamlined Sales and Use Tax Agreement, which standardizes definitions and rate structures and gives sellers state-funded software with audit immunity¹. Those three features became the template. Almost every economic nexus law passed since copies them, which is why you will rarely see a state chase a remote seller for periods before its own law took effect. The simplification project itself is covered in the Streamlined Sales Tax guide.

The types of nexus, and what creates each one

Every kind of nexus is the same idea in different clothing: a fact about your business that a state has decided is a sufficient connection. They are alternatives, not stages. You do not work through them in order — any single one is enough on its own, and a business with inventory in a state has nexus there whether or not it has sold a dollar. The taxonomy below is the map for the rest of this guide.

Categories as described by state revenue departments; see the sections below for the sourced wording of each.

Two consequences follow immediately. First, a threshold review alone is not a nexus review: it tests one row of that table. A business can be nowhere near $100,000 in a state and still owe from day one because of a single contractor. Second, the types stack. A seller can have physical nexus in three states, economic nexus in twelve, and a legacy click-through exposure in one — with three different start dates and three different remedies. That is why the review at the end of this guide starts with the footprint rather than the revenue.

Physical presence: the list states actually publish

Physical presence survived Wayfair untouched. It is still the fastest route to a collection duty, it applies with no minimum size, and it is the version most often discovered late. Washington's Department of Revenue states the standard about as plainly as any state does: physical presence "requires only more than the slightest presence"⁴. There is no de minimis rule waiting to rescue you.

Washington then publishes a list of the activities that create it. It is worth reading in full, because most of the entries describe things a business does without thinking of them as a tax event.

Activity list as published by the Washington State Department of Revenue⁴; other states publish similar but not identical lists.

The inventory trap

The third row does most of the damage. Inventory creates nexus in the state where it sits, and the state does not care that a platform decided where to put it. If a fulfillment network moves your stock to a new warehouse to shorten a delivery route, that movement can create a collection duty in a state you have never visited, from the date the pallet arrived. This is the single most common finding in a first nexus review, and it is the reason the Amazon FBA sales tax guide exists as a separate page. The same logic applies to third-party logistics providers and to consigned stock.

The trade show exception, and how narrow it is

Some states carve out conventions. Washington's is instructive precisely because of its conditions: attending or participating in one trade convention per calendar year does not create nexus for retail sales — but only if the event is not marketed to the general public, and the exception does not apply at all to a business making retail sales at the show, including taking orders received in the state⁵. Two shows in a year, a consumer-facing show, or one sale from the booth, and the exception is gone. Other states set their own day counts and revenue caps, so a national trade show calendar deserves the same review as a warehouse map.

Economic nexus: how a threshold replaces a warehouse

Economic nexus is the post-Wayfair idea that selling enough into a state is itself the substantial privilege of carrying on business there. The state publishes a number, you measure your sales into that state over a defined window, and if you exceed the number you register and collect. No people, no property and no agents are required at any point.

South Dakota's law is the reference implementation, and it has already evolved. As of August 2026 the state requires a business with no physical presence to obtain a license and collect if its gross revenue from sales into South Dakota exceeded $100,000 in the previous or current calendar year — the 200-transaction alternative that appears throughout the Wayfair opinion is no longer part of the test⁶. That single change tells you most of what you need to know about how this area moves.

Because the thresholds are similar and widely republished, it is tempting to treat this as a lookup problem: find the number, compare, done. That is where most self-service nexus reviews go wrong. The number is the least variable part. What varies, state by state, is what the number is counting, what period it is counted over, and whether a transaction test is joined to it by and or by or. Those three variables are the subject of the next section; the per-state figures live in the economic nexus guide and are applied to your data by the economic nexus calculator.

What the threshold counts: gross, retail or taxable sales

Three different definitions are in circulation, and they can produce three different answers from the same twelve months of trading. The Streamlined Sales Tax Governing Board publishes the distinction with a worked example, which is the clearest illustration of the problem anywhere in the official literature⁷.

Take a seller with $400,000 of sales into one state across 400 transactions, made up of $220,000 to wholesalers who supplied resale certificates, $75,000 to buyers claiming other exemptions such as manufacturing use, $10,000 of products that are exempt by their nature, and $95,000 of ordinary taxable retail sales.

Worked example after the Streamlined Sales Tax Governing Board's remote seller threshold terms⁷.

A wholesaler shipping mostly for resale is the classic casualty here. Under a gross-sales test it is registered and filing in a state where it has no taxable sales at all, and its returns will be nothing but exempt-sales lines backed by resale certificates. Under a retail-sales test in the neighboring state, it never registers. Same business, same year.

Five states, five sets of mechanics

The table below is not a threshold list — it is a demonstration that the surrounding mechanics differ as much as the numbers do. Figures are as of August 2026 and are quoted from each authority's own page.

Read the Texas row twice. Freight you separately stated, goods you sold for resale and sales to exempt entities all count toward the safe harbor figure⁸. A distributor can be well past $500,000 of "Texas revenue" with barely any taxable retail sales in the state. California adds a different twist: the $500,000 is measured across the retailer and all persons related to it under the federal ownership tests, so two sister companies cannot each sit under the line⁹. New York is the outlier in the other direction — you need both the dollars and more than 100 sales, so a business selling a handful of very expensive machines can ship $2 million into New York without crossing¹⁰.

The retreat from the 200-transaction test

South Dakota's 200-transaction alternative was copied almost everywhere in 2018 and 2019, and it has been unwinding ever since. It caught exactly the sellers the safe harbor was meant to protect: 200 orders at $12 is $2,400 of business, and a state was demanding registration, returns and audit exposure for it. The Streamlined Sales Tax Governing Board's state guidance records the removals with dates — North Dakota from July 1, 2019, Indiana from January 1, 2024, North Carolina from July 1, 2024, Alaska's municipal commission from January 1, 2025, and Illinois from January 1, 2026¹². Washington dropped both its transaction test and its click-through rule in 2019¹¹. Alabama never had a transaction test at all¹².

The practical rule for 2026: assume the dollar threshold governs, verify the transaction test rather than assuming it away, and never rely on a chart older than the last legislative session. Illinois in particular has moved repeatedly, which is why it has its own Illinois nexus page.

Affiliate and click-through nexus: the Amazon laws

Before economic nexus existed, states looking for a way around Quill invented one out of relationships. If a remote seller could not be reached directly, perhaps it could be reached through the in-state people helping it sell.

New York wrote the template in 2008. Its law created a presumption that a seller is a sales tax vendor if two things are true: it has agreements with New York residents who, for a commission or other consideration, refer potential customers to it "whether by link on an Internet Web site or otherwise"; and the cumulative gross receipts from sales to New York customers arising from those referrals exceed $10,000 over the preceding four quarterly sales tax periods¹³. Ten thousand dollars — two orders of magnitude below a modern economic threshold.

The detail that matters is the escape hatch. The presumption is rebuttable: New York treats it as rebutted where the seller can establish that the only activity of its resident representatives is a link on their websites and none of them does any in-state solicitation aimed at New York customers. Put a flyer campaign behind the link and the rebuttal fails¹³. A plain advertisement, by contrast, never created the presumption in the first place — the trigger is compensation tied to completed sales, not exposure.

Affiliate nexus is the sibling rule and works through corporate relationships rather than commissions: a related entity, common-ownership company or agent maintaining a market in the state can pull the remote seller in. Roughly twenty-one states had statutes of the click-through family by the time Wayfair was argued¹.

Most of these rules are now redundant, and some have been repealed outright — Washington eliminated its click-through nexus in 2019¹¹. They still matter for one reason: history. A back-period exposure, an audit of pre-2019 years, or the lookback in a voluntary disclosure agreement can all turn on whether an affiliate program created nexus years before your economic threshold did. If you ran an affiliate scheme in the mid-2010s, that is a real question, not a historical curiosity. It is also one of the patterns that draws attention in the first place, as the guide to what triggers a sales tax audit describes.

Marketplace nexus: when the platform becomes the collector

The states' second insight after Wayfair was that chasing a million small sellers is inefficient when a handful of platforms sit between them and the buyer. Marketplace facilitator laws move the collection duty onto the platform. South Dakota has required marketplace providers to license and remit on all sales they facilitate into the state since March 1, 2019, and its rule reaches a provider that facilitates for a single qualifying seller, or for two or more sellers whose combined sales meet the remote seller criteria⁶.

What that means for you as the seller behind the listing is genuinely inconsistent between states, and this is where the most expensive mistakes happen:

• Texas says a remote seller who sells only through a marketplace provider that certifies it is collecting and reporting on the seller's behalf is not required to hold a Texas permit — although all sellers must keep records of marketplace sales for at least four years⁸.
• New York says a marketplace seller that meets any of the vendor registration requirements must register and file periodic returns even though the marketplace provider remits the tax on the sales it facilitates¹⁰.
• Alaska's municipal commission asks you to include all marketplace sales when testing the threshold, but not to report those sales — the facilitator reports them¹⁴.

So "the platform handles it" is true about the money and frequently false about the paperwork. Three further points survive in every state. Your marketplace inventory still creates physical nexus wherever it sits. Your direct channel — your own site, your wholesale accounts, your phone orders — is yours to collect on. And your marketplace volume often still counts toward the threshold that pulls that direct channel into scope. The mechanics are set out in marketplace facilitator laws, with the platform-specific detail in Etsy and eBay sales tax and Shopify sales tax setup.

Trailing nexus, and how a collection duty ends

Nexus is easier to acquire than to lose. Several states apply what practitioners call trailing nexus: the collection duty continues for a period after the activity that created it stops. Washington states it directly — once nexus is established, all sales into Washington, not merely the sales connected to the triggering activity, are subject to the state's taxes "at least for the current year and the following year"⁵. Close the warehouse in March and you are still collecting through December of the next year.

Economic nexus has a quieter version of the same effect. Where the test reads "the previous or current calendar year", a year spent below the threshold does not end the obligation on the day you drop below it, because the previous year still qualifies you. You fall out at the start of the year after the year you were under — assuming you stay under.

Ending an obligation is therefore an administrative act, not something that happens by itself. Texas provides a dedicated form for remote sellers to terminate use tax responsibilities and remote seller status⁸; other states expect a final return and a closure request. Two things to get right: do not stop filing before the account is formally closed, because most states penalize a missed return whether or not tax was due, and do not close an account with unfiled periods behind it. Both are covered in how to close a sales tax account, and the filing cadence that governs the interim is in sales tax filing frequency and due dates.

Nexus below the state line: home rule, Alaska and local districts

A state is not always the unit of analysis. In home-rule states, cities and counties administer their own sales tax, define their own tax base, and can require their own registration — so a business can be correctly registered with the state and still be delinquent in a municipality. The mechanics differ enough to justify their own page: home-rule sales tax states.

Alaska is the extreme case, and the most interesting one, because it has no statewide sales tax at all. Its municipalities built the missing layer themselves. The Alaska Remote Seller Sales Tax Commission was established by intergovernmental agreement in 2019 and adopted a Uniform Code in January 2020, giving remote sellers a single registration and a single filing covering every member town¹⁴. As of August 2026, 54 cities and boroughs are members¹⁵.

Its rules contain two twists worth knowing even if you never ship to Alaska, because they show how much detail sits under the word "threshold". The statewide test is $100,000 of gross remote sales in the previous or current calendar year, and the 200-transaction alternative was removed from January 1, 2025. But sellers are told to exclude their physical-presence sales when testing that threshold and to remit those directly to the jurisdiction instead, and to register within 30 days of meeting the threshold¹⁴. A rule that says "do not count some of your sales" is exactly the kind of thing a generic threshold chart will never tell you. The wider Alaska picture is in the Alaska sales tax guide.

Once nexus exists, the local question changes shape: not whether you collect, but at what rate. Transit, stadium and cultural special taxing districts sit inside city and county lines and follow voted boundaries rather than postal ones, which is why the rate has to come from the address rather than the town name. That chain continues in how to find the rate for an address and origin versus destination sourcing, and you can resolve a single address on the rate lookup.

Nexus for taxes that are not sales tax

Sales tax nexus is one of several nexus questions, and answering it does not answer the others. The most misunderstood piece here is Public Law 86-272, the 1959 federal statute businesses often reach for when a state comes knocking.

Read its title: "Imposition of net income tax". The statute bars a state from imposing a net income tax on income derived from interstate commerce where the only in-state activity is soliciting orders for sales of tangible personal property, provided those orders are sent outside the state for approval and filled by shipment or delivery from outside the state¹⁶. A companion section defines net income tax as "any tax imposed on, or measured by, net income"¹⁷.

Three consequences follow, and each of them surprises somebody every year:

• It offers no protection at all against a duty to collect sales or use tax. That duty is not a tax on your income; it is an obligation to collect somebody else's tax.
• It offers no protection against taxes that are not measured by net income — gross receipts taxes such as Washington's business and occupation tax, or seller-privilege taxes such as Arizona's transaction privilege tax, sit outside it entirely.
• It covers only solicitation for tangible personal property. A services business, a licensor of software, and anyone whose in-state activity goes beyond solicitation are outside its shelter.

Income and franchise taxes have their own economic nexus rules besides. Texas treats an out-of-state entity with $500,000 or more of gross receipts from business done in Texas as having franchise tax nexus with no physical presence, for reports due on or after January 1, 2020⁸. Washington's $100,000 threshold is written to cover business and occupation tax as well as retail sales tax, and applies to service and wholesaling receipts rather than retail sales alone¹¹. Payroll withholding and unemployment insurance follow the employee, and registering with a Secretary of State is a separate act again. When several of these are in play at once, the Multistate Tax Commission's National Nexus Program offers a confidential, substantially uniform voluntary disclosure route with a single point of contact across participating states¹⁸.

How to run a sales tax nexus review

A nexus review is a data exercise before it is a tax exercise. The goal is a defensible list: for every state, a yes or no, and where the answer is yes, the month it became yes. Six steps get you there.

1. Pull twelve months of sales by ship-to state. Export every order with its delivery address, gross amount, freight and handling, and channel. Group by state and by rolling twelve months as well as by calendar year, because states use different windows.
2. Map your physical footprint separately. List every state holding inventory, employees, contractors, leased equipment, offices or delivery routes, including stock held by fulfillment centers. Physical presence has no threshold, so this list is checked state by state before any revenue test.
3. Test each state against its own rule, not a generic one. For every state on the list, confirm what the threshold counts, over which window, and whether the transaction test is combined with the revenue test or offered as an alternative. The base and the window change the answer more often than the number does.
4. Split marketplace sales from your direct channel. Record platform-facilitated sales separately from sales through your own site. Some states count facilitated sales toward your threshold, some excuse marketplace-only sellers from registering, and the two rules can point in opposite directions.
5. Date the crossing, not the discovery. For each state where you crossed, write down the month it happened and the registration deadline that follows from it. Liability runs from the crossing date, so the date you found out is irrelevant to the exposure.
6. Decide per state: register, disclose, or monitor. Register prospectively where you crossed recently, consider a voluntary disclosure agreement where the exposure is old, and set a monitoring threshold at roughly 70% of the limit for states you are approaching.

Why the crossing date is the whole ball game

Liability runs from the date you crossed, not the date you noticed, and the registration deadline is usually written as an offset from the crossing. Texas states it precisely: a remote seller that exceeds the $500,000 safe harbor must obtain a permit and begin collecting no later than the first day of the fourth month after the month in which it exceeded, and the Comptroller's own worked example runs from a twelve-month period ending June 30, 2022 to a permit deadline of October 1, 2022⁸.

Rule and example as published by the Texas Comptroller of Public Accounts⁸. Other states use different offsets — some expect registration within 30 days, some by the first day of the next month.

What to do with each state on the list

The output of the review is three piles, not one. States where you crossed recently get a prospective registration, which is the ordinary path described in how to register for a sales tax permit — and if several of them are Streamlined members, one application through that system covers them all⁷. States where the crossing is old enough that back tax has accumulated are candidates for a voluntary disclosure agreement, which trades a limited lookback and penalty relief for coming forward first. States you are approaching go on a watch list with an alert well below the line. The immediate practical steps after a crossing are laid out in crossed a nexus threshold, what now.

For the arithmetic itself, the economic nexus calculator compares your sales by state against current thresholds, and the multi-state sales tax calculator prices the same order across several states once you know where you must collect. If the exposure is already an assessment rather than a decision, start with defending a sales tax audit.

Misconceptions that cost real money

Most nexus disasters trace back to one of a handful of beliefs, each of which sounds reasonable and none of which is true.

"My LLC is registered in one state, so that is where my nexus is"

Formation state is one nexus fact. It does not cap the rest. A Wyoming LLC with stock in a Pennsylvania fulfillment center, a contractor in Georgia and $600,000 of shipments into Texas has four separate questions to answer, and its certificate of formation is relevant to exactly one of them. Choosing a formation state for sales tax reasons is a strategy with no mechanism behind it.

"I use a dropshipper, so I have no presence anywhere"

Drop shipping splits the transaction into two sales with two possible collection duties, and the awkward part is usually the certificate rather than the nexus: a supplier with nexus in the ship-to state has to charge you tax unless it can accept your resale certificate, and not every state accepts an out-of-state certificate from an unregistered buyer. The four-quadrant version of this problem is worked through in drop shipping sales tax.

"The marketplace collects, so I am covered"

Covered on the platform's sales, in most states. Not covered on your own site, not covered for your wholesale accounts, and not covered for the inventory the platform is storing on your behalf. This is the most expensive single misconception in ecommerce, because it feels verified every time you look at a platform payout report.

"I will just register everywhere to be safe"

Registration is not a precaution; it is a commitment. Every registration creates a permanent filing obligation, including zero returns for periods with no sales, and most states penalize a late zero return exactly as they penalize a late one with tax due — see sales tax penalties and interest. Registering in every state that levies a sales tax to avoid thinking about the six where you actually have nexus is a permanent annual cost paid to avoid a one-off analysis.

"Nexus and registration are the same thing"

They are opposites in kind. Nexus is a fact about your business that exists whether or not anybody has noticed. Registration is an act you perform. You can have the first without the second, which is how uncollected tax accrues, and the second without the first, which is how businesses end up filing zero returns in states they never sold into.

"My products are not taxable, so the threshold cannot catch me"

Most thresholds are measured on gross or retail sales, not taxable sales, so exempt products count toward the number that forces you to register. Whether you then collect anything is a separate question answered by taxability rules. Software sellers get this wrong most often, which is why the SaaS compliance playbook and digital products sales tax treat nexus and taxability as two separate passes over the same data. And once you do collect, the arithmetic is the easy part — the how to calculate sales tax guide and the sales tax calculator handle it.

Where to go next

• Economic nexus thresholds by state — the current numbers this page deliberately leaves out.
• Economic nexus calculator — your sales by state, tested against those thresholds.
• You crossed a threshold — what now — the first ninety days, in order.
• Marketplace facilitator laws — who collects when a platform is in the middle.
• Texas, California, New York and Washington rate pages — the states whose nexus wording this guide quotes.