A Guide to US Sales Tax Nexus for E-commerce Sellers

Last verified: June 2026

Most e-commerce sellers don't find out they have a sales tax problem until a notice arrives from a state they've never thought about. By then, the back-tax exposure is real, interest has been compounding, and registrations that should have been filed two years ago are overdue. The good news: the rules, while spread across 46 taxing jurisdictions, are more predictable than they look. This guide covers everything — from the Supreme Court ruling that rewrote e-commerce tax law to the specific thresholds you need to watch in 2026 — and gives you a five-step framework you can act on today.

What is sales tax nexus (and why it matters in 2026)

Sales tax nexus is the connection between a business and a state that creates a legal obligation to collect and remit sales tax there. Without nexus, a state has no authority to demand you collect tax from its residents. With it, you're legally required to register, charge the correct rate, and file returns on whatever schedule that state dictates — monthly, quarterly, or annually, depending on your volume.

For most of US commercial history, nexus meant physical presence: a shop, a warehouse, employees on the ground. A mail-order company in Ohio selling to customers in Montana had no Montana nexus and owed Montana nothing. That held until June 21, 2018, when the Supreme Court decided South Dakota v. Wayfair, Inc. — and rewrote the rules entirely.

The Court ruled that states could require out-of-state sellers to collect sales tax based solely on their economic activity within that state, even with zero physical presence. Every state with a sales tax moved quickly to pass economic nexus laws. By 2026, all 45 states that levy a statewide sales tax, plus Washington D.C., have economic nexus rules on the books.

Why does this matter specifically now? Because states are actively enforcing. Revenue departments have become sophisticated about using marketplace data, payment processor records, and third-party analytics to identify non-compliant sellers. The era of quietly selling into states you'd never registered in is over. Exposure typically runs back three to four years, and penalties plus interest can dwarf the original tax owed.

Nexus is also foundational to clean operations in a way that's easy to underestimate. If you're managing inventory across multiple channels — Shopify, Amazon, wholesale — keeping stock in sync across channels is hard enough without surprise tax registrations landing on your desk. Getting ahead of nexus means fewer operational fires later.

The core principle: nexus is the threshold trigger. Once crossed, the obligation is immediate, retroactive to when it was crossed, and doesn't disappear until you formally withdraw your registration.

Physical nexus vs. economic nexus: key differences for online sellers

Physical nexus and economic nexus are two distinct legal tests — and as an e-commerce seller, you may be subject to both in the same state at the same time.

Physical nexus

Physical nexus is established through tangible presence in a state. The most common triggers are:

• A registered office or retail location — even a home office counts if your business is registered there
• Employees or contractors — a remote employee living in Colorado creates Colorado nexus for your business
• Inventory stored in a warehouse or fulfilment centre — this is where Amazon FBA gets complicated (more on that shortly)
• Trade show attendance — some states treat temporary physical presence at trade shows as nexus-creating
• Delivery vehicles — operating company-owned vehicles that cross state lines can trigger nexus in some jurisdictions

Physical nexus has no revenue threshold. The moment your inventory lands in a state's fulfilment centre, or your first employee moves there, nexus is established. That's it. No revenue minimum, no grace period.

Economic nexus

Economic nexus is triggered by crossing a state's defined threshold of sales activity — measured by revenue, transaction count, or both. Since Wayfair, states have been free to set their own thresholds, and while the market has converged heavily toward a $100,000 revenue standard, the specifics still vary.

The key operational point: economic nexus looks backward at a measurement period. Most states use either the previous calendar year or the current calendar year on a rolling basis. So if your sales into Michigan crossed $100,000 in March 2026, you had Michigan nexus from the day you crossed that threshold — not from the start of the next quarter.

The practical difference

For a typical growing e-commerce brand, physical nexus is usually limited to your home state plus wherever your 3PL or fulfilment partners operate. Economic nexus, by contrast, scales with your revenue. A brand doing $2 million in annual US sales spread across the country will likely have economic nexus in every high-population state — California ($500,000 threshold), Texas ($500,000), New York ($500,000 and 100 transactions), and a long tail of $100,000-threshold states beyond those — whether or not they've ever set foot in any of them.

One more nuance worth flagging: affiliate nexus and click-through nexus. Some states created these categories before Wayfair to catch sellers with referral or affiliate relationships with in-state businesses. They're less commonly discussed now that economic nexus is universal, but they remain on the books in several states and can catch sellers who are otherwise below the economic nexus threshold.

The bottom line: physical nexus is binary (you either have presence or you don't), while economic nexus scales with your sales activity — making it the primary ongoing compliance challenge for growing brands.

How Amazon FBA inventory creates physical nexus complications

Amazon FBA creates physical nexus in every state where Amazon stores your inventory — and because Amazon controls where that inventory goes, you often have no say in the matter. This is one of the most misunderstood nexus risks in e-commerce, and it catches sellers off guard constantly.

When you ship product into the FBA network, Amazon uses its own algorithms to distribute your inventory across its fulfilment centres for efficiency. You might send a pallet to a centre in Kentucky, and within days Amazon has moved portions of that inventory to centres in Pennsylvania, California, Texas, and Nevada. You now have inventory — and therefore physical presence — in five states. All five have nexus. All five require registration.

Amazon does provide an Inventory Event Detail Report (available in Seller Central) that shows which states have held your inventory over any given period. This is your starting audit document. If you're an FBA seller and you haven't pulled this report, do it now. The list will probably be longer than you expect.

A worked example: say you're a UK-based brand that launched on Amazon US in 2024, shipping into a single FBA centre in California. By 2026, Amazon has redistributed your inventory and it's touched fulfilment centres in 18 states. You have physical nexus in all 18. Your revenue into most of those states is well below $100,000 — so you wouldn't have economic nexus — but physical nexus has no threshold. You should have been registered and collecting from day one of inventory storage.

This matters doubly for non-US sellers. There's no foreign-seller exemption in US sales tax law. A brand based in Germany, Australia, or Canada using FBA has the same obligations as a brand in Ohio. The nationality of the business is irrelevant; what matters is where the inventory is. Even if you live outside the United States, selling via FBA or establishing any other type of physical nexus means you must comply with the sales tax rules of every state where your inventory is stored.

But here's where it gets slightly more nuanced. Amazon is a marketplace facilitator in all US states that have marketplace facilitator laws — which is essentially all of them. This means Amazon collects and remits sales tax on orders placed through Amazon's marketplace on your behalf. So for your Amazon channel, the collection burden is largely handled. The complication is that physical nexus created by FBA can still affect your obligations on other channels — your Shopify store, your eBay listings, your direct wholesale invoices. If FBA puts your inventory in Texas, you have Texas physical nexus, which means you need to collect Texas sales tax on your Shopify sales too, not just your Amazon sales.

This is why inventory visibility across channels matters so much operationally. If you're running Shopify alongside Amazon, your nexus exposure from FBA ripples across your entire sales operation, not just the Amazon channel. The pattern we see repeatedly: strong Shopify revenue flowing into states where FBA had already created physical nexus months earlier, zero tax being collected on any of it, years of exposure building quietly in the background. By the time anyone notices, the back-period is painful.

One practical note: some sellers use Amazon's "Inventory Placement" programme to restrict where Amazon initially sends inventory. This can reduce (but not eliminate) the spread of nexus states. It's worth discussing with a tax adviser if controlling your nexus footprint is a priority — though Amazon still retains the right to redistribute.

The core FBA nexus rule: Amazon's marketplace facilitator status handles collection on Amazon orders, but FBA-created physical nexus extends your collection obligations to all other sales channels you operate.

State-by-state economic nexus thresholds: 2026 updates and trends

The most common economic nexus revenue threshold is $100,000 in sales into a state within a calendar or rolling 12-month period. The trend in 2026 is further simplification: states are dropping dual-threshold rules (revenue and transaction count) and moving to revenue-only triggers.

The clearest recent example: Illinois eliminated its 200-transaction threshold on January 1, 2026. Previously, an Illinois nexus trigger required either $100,000 in sales or 200 or more separate transactions. The transaction count element is now gone. Illinois nexus today is purely revenue-based: cross $100,000 and you're in. Multiple states have been moving in the same direction — simplifying by ditching transaction-based thresholds and relying on revenue alone.

Why does dropping the transaction threshold actually matter? Because it removes a quirk that hit sellers of lower-value, high-volume goods differently from sellers of high-value, low-volume goods. A seller moving 300 units at $30 each ($9,000 total) could previously trigger Illinois nexus purely on transaction count, well before getting close to the revenue threshold. Under the new rule, they're clearly below nexus. A seller with 50 transactions at $2,500 each ($125,000 total), on the other hand, now has straightforward nexus on revenue alone. Cleaner for everyone.

A few states worth flagging individually for 2026:

• California — $500,000 revenue threshold, one of the highest in the country. No transaction-count trigger. Most brands will hit this eventually, but smaller sellers get a longer runway.
• Texas — $500,000 threshold as well. Texas also runs some of the most aggressive audit programmes in the country, so compliance here matters.
• New York — $500,000 and 100 transactions (both must be met). One of the few remaining dual-threshold states.
• Kansas — No threshold at all. Any remote seller with any amount of Kansas sales technically has economic nexus. Kansas is an outlier, but it's real.
• Missouri — A relatively late adopter of economic nexus legislation, now fully in force with a $100,000 threshold.

And a note for international sellers: US sales tax operates entirely at the state level, not the federal level. There's no federal sales tax. You're dealing with up to 46 separate taxing authorities — 45 states plus D.C. — each with its own registration portal, filing schedule, and rate structure. No single federal registration covers you. It's genuinely complex. It's also manageable, once you stop trying to hold it all in a spreadsheet.

One further complexity worth naming: product taxability. Economic nexus tells you whether you need to collect tax in a state. It doesn't tell you which of your products are actually taxable there. The taxability of digital goods versus physical products varies significantly by state — some tax digital downloads, some don't, some apply reduced rates. Clothing is tax-exempt in Minnesota and New Jersey but taxable in most other states. Grocery food is generally exempt, but "prepared food" isn't — and where that line sits is state-specific. If your product catalogue spans multiple categories, you need taxability determinations for each significant state, not just a yes/no nexus answer.

Honestly, the threshold maths is the part most brands have already figured out. The taxability question is where things tend to quietly go wrong. Knowing you have nexus in Pennsylvania means nothing if you don't also know that most clothing items are exempt from Pennsylvania sales tax.

We covered the broader question of how compliance layers interact as brands scale into new markets in our guide to the international CPG e-commerce operations stack.

For 2026: assume $100,000 in annual revenue into any state triggers economic nexus unless you've confirmed otherwise, check for recent threshold changes before filing, and always layer taxability analysis on top of nexus analysis.

A five-step framework for managing multi-state sales tax compliance

Once you've accepted that multi-state compliance is a real operational requirement, the question isn't whether to act — it's where to start. Here's the sequence that actually works.

Step 1: audit your current nexus footprint

Start with a complete picture of where you might already have nexus. Pull three data sets:

• Your business registration and facilities — where are you incorporated, where do you have offices, where do employees live?
• Your FBA Inventory Event Detail Report — which states have held your Amazon inventory in the past 12 months?
• Your sales-by-state data — broken out by channel (Amazon, Shopify, etc.), for the trailing 12 months and calendar year to date

Cross-reference sales-by-state against each state's current threshold. Flag every state where you've crossed the revenue threshold (and note where you're approaching it). Add every FBA-touched state regardless of revenue. The union of those two lists is your nexus footprint.

This is where good inventory management data becomes directly relevant to your tax compliance work. If you can't tell at a glance which states hold your inventory right now, your nexus audit will be incomplete from the start. Multi-channel inventory management with real-time visibility across fulfilment locations makes this step dramatically faster.

Step 2: register in every state where you have nexus

Registration is mandatory before you start collecting. Collecting without registering — or collecting without remitting — is worse than not collecting at all, because you've taken money from customers that you're now failing to pass on. Every state requires sellers to register with its department of revenue before collecting tax. Most have online portals. Some states also require you to register with local jurisdictions separately (Louisiana is notorious for this).

If you're registering retroactively — meaning you've had nexus for some time without collecting — look into each state's voluntary disclosure agreement (VDA) programme before registering cold. Most states offer VDAs that limit your back-period exposure, typically to two or three years rather than the full open period, and often waive penalties in exchange for voluntary disclosure. That's usually a far better outcome than waiting for an audit notice.

Practically: if your nexus footprint spans more than five or six states, the registration workload alone is significant. Many brands use a sales tax attorney or CPA to handle the initial multi-state registration batch. It's a one-time cost with meaningful risk-reduction value.

Step 3: configure tax collection in your sales channels

Once registered, you need to collect the right rate from customers in each nexus state. Both Shopify and Amazon have tax settings that let you configure collection by state. For Shopify, that means going into your tax settings, enabling collection for each registered state, and — critically — applying product-specific tax rules where your items have exemptions or special rates.

A few things to get right here:

• Origin vs. destination sourcing — most states are destination-based (tax is based on where the customer is), but some states (like Texas for in-state sellers) are origin-based. This affects which rate you charge.
• Local rates — many states have county and city taxes on top of the state rate. Chicago's combined rate, for example, is significantly higher than Illinois's state rate alone. Your platform should handle this automatically if configured correctly, but verify.
• Exemption certificates — if you sell B2B and have wholesale customers, you need a process for collecting and storing resale exemption certificates from exempt buyers. Don't overlook this if wholesale is part of your model. We covered the operational complexity of B2B sales in our guide to the modern B2B wholesale operations stack.

Step 4: file and remit on schedule

Registration assigns you a filing frequency — monthly, quarterly, or annually — based on your sales volume in that state. High-volume states will typically require monthly filings. This means you could be filing returns in 20+ states on staggered schedules simultaneously.

Missing a filing isn't the same as missing a payment. Filing a return (even a zero return, if required) is a separate obligation from remitting the tax. States charge penalties for late filings even if you subsequently pay everything owed.

The mechanics of remittance vary: some states accept ACH pulls, some require ACH credits initiated by you, some accept credit cards with processing fees. Most states now have electronic filing requirements for sellers above certain thresholds. Check each state's portal. And note that some states require you to file a final return and formally close your account if you cease doing business there — you can't just stop filing.

For brands that also sell into EU markets, you'll recognise this rhythm. It's structurally similar to VAT filing obligations — just multiplied across 45 jurisdictions instead of one. If you're already thinking about EPR compliance alongside tax, our upstream sustainability stack for e-commerce is worth reading for context on how these compliance layers interact.

Step 5: build a monitoring cadence

Nexus isn't a one-time project. States change thresholds, your sales grow into new states, your fulfilment network changes. You need a regular review cycle — at minimum annually, ideally quarterly.

Your monitoring cadence should cover:

• Sales-by-state trending — are you approaching the threshold in any states where you're not yet registered? A brand doing $80,000 in annual Michigan sales is close enough to warrant setting up registration now, not after crossing.
• Regulatory changes — states adjust thresholds, filing frequencies, and taxability rules. Illinois's January 2026 change is a recent example; there will be others. Subscribing to a sales tax news service, or having your accountant flag changes, is worth the effort.
• Inventory location changes — if you add a new 3PL, change your FBA enrolment settings, or open a new warehouse, revisit your physical nexus map immediately.
• Returns and credits — sales tax on returned goods can generally be reclaimed, but the process varies by state. If your return rates are material (above, say, 10% of gross sales), build a refund reconciliation process into your remittance workflow.

On automation: sales tax compliance software can handle rate calculation, filing, and remittance across states. For brands above a certain revenue level, this isn't optional — the manual burden of multi-state compliance becomes genuinely unmanageable. Evaluate your options, but make sure any tool integrates cleanly with your actual sales channels rather than requiring manual data exports. Accurate integrations across your tech stack are what make automated compliance actually reliable.

For non-US sellers specifically: add one more layer to your monitoring cadence. Currency conversion, transfer pricing between your foreign entity and your US operations, and the interaction between US sales tax and your home country's VAT or GST obligations all need attention. The US has no tax treaty mechanism that eliminates state-level sales tax obligations for foreign businesses — you're fully subject to the same rules as any US-based seller.

The five steps in one sentence: audit your footprint, register before collecting, configure rates precisely, file on every deadline, and build quarterly monitoring into your ops calendar.

Frequently asked questions

What creates sales tax nexus for an online seller?

Sales tax nexus is created either by physical presence in a state (offices, employees, inventory in a warehouse or fulfilment centre) or by crossing that state's economic nexus threshold — typically $100,000 in annual sales. Since the Supreme Court's 2018 South Dakota v. Wayfair ruling, physical presence is no longer required; revenue alone is sufficient to create a collection obligation in most states.

Does using Amazon FBA create sales tax nexus?

Yes — Amazon FBA creates physical nexus in every state where Amazon stores your inventory, because having inventory in a state constitutes physical presence. Amazon handles tax collection on orders placed through its own marketplace (as a marketplace facilitator), but FBA-created physical nexus extends your collection obligation to all other sales channels you operate, such as your Shopify store or direct wholesale sales.

How do I know if I have economic nexus in a state?

You have economic nexus in a state if your sales into that state exceed its defined threshold — most commonly $100,000 in annual revenue — within the measurement period that state specifies (usually the prior calendar year or a rolling 12 months). Pull your sales-by-state report from each selling platform, compare each state's total against the current thresholds, and flag every state where you've crossed the threshold or are approaching it. Note that some states, like Kansas, have no minimum threshold at all.

What is the difference between physical and economic nexus?

Physical nexus is triggered by a tangible presence in a state — an office, an employee, or inventory — and has no revenue threshold; any presence creates it. Economic nexus is triggered purely by sales activity crossing a state's defined revenue (and sometimes transaction) threshold, regardless of whether you have any physical footprint there. As an e-commerce seller, you can have both types simultaneously in the same state — physical nexus from FBA inventory and economic nexus from high sales volume.

What to do next

Pull your FBA inventory report and your sales-by-state data this week. That's the step most brands keep deferring, and it's the one that matters most. Even a rough mapping will tell you whether you're materially exposed or broadly compliant. In our experience, the answer is usually somewhere specific and actionable: a handful of states where registration is overdue, and a much longer list where you're clearly below threshold and can stop worrying about them entirely.

One thing that compounds the complexity: when you're filing across 20 states, reconciling your settlement data accurately becomes critical. If your channel revenue figures don't match what's in your books, your sales-by-state numbers will be wrong, and your nexus analysis will be wrong as a result. That's where clean financial data matters as much as tax knowledge. Ceendesis Accounting reconciles payouts from Amazon, Shopify, eBay, Etsy, Walmart, TikTok Shop, Square, and WooCommerce — splitting each settlement into sales, fees, refunds, reserves, and tax with per-product COGS tracking, then posting clean accrual-correct journals to your ledger. It's built around Xero today (QuickBooks Online support is rolling out; no Sage yet) — but if you're running Xero and selling across multiple channels, having accurate per-channel revenue figures flowing cleanly into your accounts is foundational to everything else, including reconciling your settlements in a way your accountant can actually work with.

Sales tax compliance is unglamorous work. But it compounds — in both directions. Get the nexus audit done now, register where you should, and build the monitoring cadence into your ops calendar before a state change catches you out. Because they do change. Illinois just did. Others will.