What Nexus Exposure Actually Looks Like: A Case Study

Nexus exposure stays abstract until you walk through how it actually accumulates in a real business. The scenario below is a composite, drawn from patterns I see over and over across e-commerce and multi-channel clients. No single business is being described, but every piece of it happens exactly this way in practice. I'm writing it out because the danger isn't in any one decision. It's in how ordinary each decision looks on its own.

Year one: a simple, compliant start

A client sells home goods exclusively through one major marketplace. Because the marketplace is a facilitator, it collects and remits sales tax on the client's behalf everywhere that's required. From the client's view, and their accountant's, sales tax is handled. Nothing to file, nothing to monitor. This is accurate for year one. It will not stay accurate.

Year two: growth creates the first gap

Business is good, so the client launches their own direct storefront to cut marketplace fees on a growing share of revenue. Completely reasonable. It's also the moment exposure begins, because direct sales through their own site are not covered by the marketplace's collection. The client is now responsible for determining where they have economic nexus and registering, collecting, and filing accordingly.

Nobody flags it internally. The client doesn't see a tax event, they see a new sales channel. The bookkeeper is focused on categorizing the new revenue, not on whether a collection obligation just switched on. By the end of year two, direct sales alone have crossed economic nexus thresholds in several states, and the client is registered in none of them. In more than one of those states, the marketplace volume is also being counted toward the threshold, which pulled them over the line sooner than their direct sales alone would have.

Year three: the gap widens

The client adds a wholesale arm, selling to small retailers who stock their products. Wholesale sales are typically exempt when properly documented with a resale certificate, but that requires actually collecting and validating those certificates, and the client has no process for it. At the same time, they enroll in a fulfillment program that distributes inventory across third-party warehouses to speed up shipping. That creates physical presence nexus in new states, independent of any sales activity at all, because warehoused inventory is enough to establish nexus in most states.

By the end of year three, obligations are stacking from three separate sources: economic nexus from direct sales, physical nexus from warehoused inventory, and undocumented wholesale exemptions that an auditor could disallow. Nobody working with this client, including the client, has connected those three threads into one picture of exposure.

How it surfaces

The exposure doesn't surface through the client's own review. It surfaces because one of the states where their inventory is warehoused sends a notice, prompted by data the state received from the fulfillment provider. The notice asks about unregistered activity going back to when the fulfillment program began. That look-back now sweeps in the wholesale exemption problem and the direct-sales nexus gap too, because once a state opens the door, it tends to ask about everything, not just the original trigger.

I've also seen this arrive a quieter way. A prior provider deregistered the client from a state years earlier and the obligation was later re-established without anyone catching it, leaving a stack of unfiled returns nobody was watching. Either path ends in the same place: back taxes, penalties, and interest across multiple states, plus the cost of reconstructing years of transaction data to pin down exact liability in each one.

What would have changed the outcome

Nothing here required a dramatic mistake. Launching a direct site, adding wholesale, using a fulfillment network, each was a normal, healthy business decision. The exposure built entirely because nobody reviewed the client's nexus footprint as those decisions happened.

A standing practice of reviewing nexus at each meaningful change, a new channel, a new fulfillment arrangement, a new state, would have caught each one individually, when the fix was a registration and a filing instead of a multi-year audit. The same goes for exemption certificate collection on the wholesale accounts. That's a documentation habit that costs almost nothing to maintain and becomes expensive only in its absence. It's the cheapest insurance in this whole scenario, and it's the one almost nobody buys until an auditor asks for certificates that were never collected.

The takeaway for firms

This client didn't do anything unusual. Adding channels, adding fulfillment complexity, adding B2B alongside B2C, that's close to the norm for a growing e-commerce business. Which is exactly why this belongs in standing client service rather than something you address only when a client asks. The most exposed businesses aren't the ones cutting corners. They're the ones growing in completely ordinary ways, with no one checking whether their tax obligations grew right alongside them.

Sponsored Content: This article is generously brought to you by one of our valued sponsors. Their support enables us to continue delivering expert insights and the latest industry trends to our dedicated community of accounting professionals.