US Sales Tax Nexus for Foreign Ecommerce Sellers: Hidden Triggers and Compliance Steps

Background

Foreign e-commerce sellers can create US sales tax nexus even without a US office, employees, or a legal entity. Since the 2018 South Dakota v. Wayfair decision, many US states can require remote sellers to register, collect, and remit sales tax based on economic activity alone. 

This means that sales volume, transaction counts, stored inventory, marketplace activity, trade shows, affiliate marketing, or fulfilment arrangements can all create state-level obligations.

For non-US companies, the main risk is not always obvious. A seller may be located in Europe, Asia, or Latin America but still have sales tax obligations in California, Texas, Florida, New York, or other states. The obligation is determined state by state, and each state may have different thresholds, registration rules, product taxability rules, filing periods, and marketplace facilitator provisions.

The safest approach is to map sales, inventory, fulfilment, marketplaces, affiliates, and historic exposure by state. Where past noncompliance exists, Voluntary Disclosure Agreements can often reduce penalties and limit historical lookback periods.

What Sales Tax Nexus Means

Sales tax nexus is the legal connection between a seller and a US state that allows the state to require the seller to register, collect sales tax from customers, file returns, and remit the tax.

For foreign e-commerce sellers, nexus can arise even when the seller has neither US incorporation nor direct physical presence. The key question is whether the seller’s activities, sales, inventory, or relationships create enough connection with a particular state.

Nexus is not a federal concept applied uniformly across the US. It is mainly determined at the state level. As a result, a seller may have nexus in one state but not in another, even if it sells similar products to customers in both.

The Impact of the Wayfair Decision

Before Wayfair, many sellers relied on the assumption that physical presence was necessary before a state could impose sales tax collection duties. That approach is no longer safe.

The Supreme Court’s Wayfair decision allowed states to impose sales tax obligations on remote sellers based on economic presence. In practical terms, if a seller makes enough sales into a state, the state may require registration and sales tax collection even if the seller has no warehouse, staff, or office there.

Many states adopted economic nexus thresholds after Wayfair. A common model is based on annual sales revenue in the state, often around USD 100,000, although some states use different thresholds or have removed transaction count tests. Therefore, foreign sellers must track sales by destination state, not only total US revenue.

Economic Nexus: Sales Volume as a Trigger

Economic nexus is triggered when a seller exceeds a state’s sales threshold. This threshold may be based on gross sales, taxable sales, transaction count, or a combination, depending on the state.

For example, a Lithuanian brand selling skincare products into the US may have no US office and no US employees. If it sells USD 130,000 of products to customers in one state during the relevant period, that state may treat the brand as having economic nexus and require sales tax registration.

The common mistake is monitoring US sales as one total number. A seller may think its US activity is modest, but state-level data may show that several individual states have already crossed their thresholds. This is especially common for businesses selling through multiple channels, such as Shopify, Amazon, Walmart, Etsy, and direct wholesale orders.

Inventory and Fulfilment Nexus

Inventory is one of the most common hidden nexus triggers. If a foreign seller stores goods in a US warehouse, third-party logistics facility, marketplace fulfilment centre, or Amazon FBA location, many states may treat that inventory as physical presence.

This can create a nexus even before the seller crosses an economic nexus threshold. The relevant issue is where the stock is physically located, not where the seller is incorporated or who owns the warehouse building.

For example, a UK seller sends products to Amazon FBA. Amazon may move the inventory between warehouses in several states. The seller may not actively choose those locations, but the inventory can still create nexus in the states where the goods are stored. If the seller does not obtain inventory location reports, it may not realise it has created obligations in multiple states.

Foreign sellers should request warehouse location reports from fulfilment providers and compare those locations with state nexus rules.

Marketplace Facilitator Rules

Marketplace facilitator laws can reduce the seller’s direct collection obligation for marketplace sales, but they do not eliminate all sales tax risk.

In many states, marketplaces such as Amazon, Walmart, Etsy, and eBay are required to collect and remit sales tax on sales they facilitate. If a foreign seller sells only through a marketplace, the platform may collect tax on customer transactions.

However, this does not mean the seller can ignore sales tax completely. Marketplace collection may not cover direct website sales, wholesale sales, stock movements, inventory-based nexus, or states where separate registration or reporting is required. The seller may also need records showing which transactions were collected by the marketplace.

For example, a German seller uses Amazon for 70 percent of US sales and Shopify for 30 percent. Amazon may collect tax on marketplace transactions, but the seller must separately assess whether its Shopify sales create economic nexus and whether tax must be collected on direct sales.

Affiliate, Click-Through, and Event Nexus

Some nexus triggers arise from marketing rather than inventory or sales volume. Affiliate nexus or click-through nexus may arise where a seller uses in-state partners, referrers, influencers, or websites to generate sales for commission.

For example, a foreign apparel brand pays a New York-based influencer a commission for sales generated through referral links. Depending on the state rules and the structure of the arrangement, this relationship may contribute to nexus analysis.

Temporary physical activity can also matter. Trade shows, fairs, pop-up shops, product demonstrations, or sales events may create nexus in some states. Even short-term attendance can trigger registration or filing duties where the state treats event activity as physical presence.

Foreign sellers should review US marketing campaigns and event participation alongside sales and inventory data.

Digital Products and SaaS

Foreign sellers often assume that sales tax applies only to physical goods. This is not correct. Many states tax digital products, software, SaaS, streaming, downloads, online content, or electronically delivered services, but the rules differ widely.

For example, a foreign SaaS provider may have economic nexus in a state because of subscription revenue. Whether it must collect sales tax depends on that state’s treatment of SaaS. One state may tax SaaS as a taxable service, while another may exempt it or treat it differently.

Digital businesses should therefore review both nexus and product taxability. Having nexus does not automatically mean every product is taxable, but it does mean the seller must know the state’s rules.

Discovering Historical Exposure

Foreign sellers usually discover US sales tax nexus late. Common triggers include tax authority notices, marketplace compliance requests, investor due diligence, acquisition reviews, accounting audits, or internal finance reviews.

By that point, the seller may have several years of uncollected tax. The exposure may include unpaid sales tax, interest, penalties, late filing penalties, and administrative burdens. The risk is higher where the seller collected tax but failed to remit it, because states treat collected but unremitted tax very seriously.

A structured nexus review should identify when nexus began in each state, whether sales were taxable, whether tax was collected by a marketplace, and whether voluntary disclosure is available.

Voluntary Disclosure Agreements

A Voluntary Disclosure Agreement (VDA) is a state programme that allows a taxpayer to come forward before being contacted by the state. In exchange, the state may limit the lookback period and waive or reduce penalties.

VDAs are often useful where a seller had a nexus for several years but never registered. The seller can approach the state, often anonymously through a representative, quantify the exposure, agree on the lookback period, register, file past returns, and pay tax and interest.

For example, a foreign e-commerce seller discovers that it has had inventory in three US states for four years. Instead of registering immediately and exposing itself to open-ended historical questions, it may first evaluate whether VDAs are available. A VDA can provide a cleaner route into compliance and reduce the risk of wider penalties.

VDAs should be handled carefully. If a state has already contacted the seller, voluntary disclosure may no longer be available.

Practical Compliance Framework

Foreign e-commerce sellers should manage US sales tax in a structured way.

First, they should map sales by state, including revenue, transaction count, customer location, product type, and channel. This should include marketplace sales and direct sales, even where the marketplace collected tax.

Second, they should map physical presence. This includes inventory, warehouses, fulfilment centres, staff, contractors, events, affiliates, and other in-state activities.

Third, they should compare the data against each state’s economic and physical nexus rules. This shows where registration is required and where monitoring is sufficient.

Fourth, they should review product taxability. A seller must know whether its goods, digital products, SaaS, shipping charges, subscriptions, or services are taxable in each nexus state.

Fifth, they should address historic exposure before registering where possible. In some cases, this means using VDAs before making direct contact with state tax authorities.

Finally, the seller should implement ongoing compliance. This includes sales tax calculation, return filing, marketplace reconciliation, exemption certificate management, and regular nexus reviews.

How to Stay Compliant

1StopVAT helps foreign e-commerce sellers identify, manage, and resolve US sales tax nexus exposure. The process usually starts with a nexus risk assessment covering economic thresholds, inventory locations, marketplaces, affiliates, events, and direct sales.

Where historic exposure exists, support may include quantifying liabilities, prioritising states, preparing VDA strategies, managing registrations, and setting up ongoing filings. For current compliance, 1StopVAT can help configure systems, reconcile marketplace and direct sales data, monitor thresholds, and prepare state returns.

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