A client called me last month. They had pulled out of Amazon FBA in November 2025 after the new fee schedule wrecked their margins on small-ticket items. Six months later, they got a sales tax notice from California asking why they had stopped filing returns even though they still had a registration on file.
The short answer: trailing nexus. The longer answer is the reason a lot of sellers are walking into surprises this year as they prune marketplaces, change fulfillment networks, or move inventory out of states where they no longer want a footprint.
If you’re considering leaving a marketplace, or you already have, this is the part most consultants don’t explain until you’re already in the notice loop.
Why trailing nexus exists
Most state sales tax laws say you have nexus the moment you create a sufficient connection: physical presence, economic threshold, or marketplace storage of inventory. The catch is that the connection doesn’t end the moment you stop the activity that created it.
California’s regulation is the most cited example. After you stop the activity that triggered nexus, you remain a retailer engaged in business in the state for as long as the lingering effects continue, plus typically the rest of the calendar quarter and the following one. Texas applies a similar 12-month trailing rule. New York and Pennsylvania use language that effectively gives them nexus until the end of the calendar year following the year you stopped.
The states are not unreasonable about this. The logic is that customers who bought from you while you had nexus might return for a second purchase, or you might still have receivables, or you might still be advertising. They want collection and filing to continue while there’s residual activity.
The marketplace storage trap
Amazon FBA is the cleanest example. The moment Amazon places your inventory in a fulfillment center in a given state, you have physical nexus there. This is true in every state that has a sales tax. It’s also true even though Amazon is the marketplace facilitator and is collecting and remitting on your behalf.
That collection-and-remit arrangement covers tax on Amazon-channel sales. It does not relieve you of the underlying nexus obligation. If you also sell on Shopify, your own website, or any non-Amazon channel into that state, you owe the tax on those sales. And when you leave FBA, the inventory has to actually move out and a return has to be filed showing zero activity, before you can deregister.
The seller who called me had pulled out of Amazon, but their last inventory hadn’t fully cleared until late January 2026. Three states (California, Texas, and New Jersey) treated the period through end of Q1 as continued nexus. Two more (New York and Pennsylvania) treated nexus as continuing through the end of 2026 because the activity had crossed a threshold during the calendar year.
They thought they had cleanly exited in November. They actually have filing obligations in five states through 2026.
State-by-state framework
Trailing nexus rules are not consistent. Some patterns to know.
End-of-quarter-plus-one states: California, Florida, and a handful of others end nexus at the close of the calendar quarter you ceased the activity, plus the following quarter. Practical effect: you usually have one or two more returns to file.
Calendar-year-trailing states: New York, Pennsylvania, Massachusetts, and several others extend nexus through the end of the calendar year following the year you stopped. If you stopped in October 2025, you may file through December 2026.
Twelve-month-trailing states: Texas applies a 12-month rule from the date activity ceased. The clock is on a rolling basis, not calendar.
No-trailing states: A few states (Wyoming, Montana for the limited use cases that apply, and others without sales tax) have no trailing concept because nexus can be ended administratively when activity stops.
Economic-nexus-only states: If your only nexus was economic (you crossed a sales or transaction threshold but never had inventory or employees in the state), the nexus typically rolls off after one full year of falling below the threshold. Some states require you to formally close the account.
What to do before you leave a marketplace
Three steps will save you from the notice loop.
First, identify every state where the marketplace is creating nexus for you right now. For Amazon FBA, pull your inventory event detail report and list every state where your inventory has been stored in the past 12 months. For Walmart WFS, run the equivalent. For 3PLs, list every facility location.
Second, plan the wind-down. If you can time your exit to coincide with a quarter end, you reduce the trailing exposure. Pulling inventory out in mid-November means you may owe a Q4 return in some states and another full year in others. Pulling out in late December means you owe one more Q4 return and you’re done in most jurisdictions.
Third, file the final returns and deregister deliberately. Most states won’t deregister you automatically. They’ll keep your account active and assess fees or estimated tax until you formally close. The forms vary by state. The work is paperwork-heavy but mechanical. Do it once and you’re clean.
If you’ve already left and are getting notices
This is the situation most sellers actually find me in. They left months ago, they’re getting notices now, and they’re trying to figure out what they owe and what they don’t.
Don’t ignore the notices. State response windows are short (often 30 to 60 days), and after that the state will assess on its own estimate, which is almost always higher than reality.
Pull the actual sales activity for each state for the period in question. If your post-exit sales into that state were zero on the channels that were creating nexus, you owe a return showing zero, not unpaid tax. The notice is a request for the return, not necessarily a demand for tax.
If there were sales (because Amazon kept selling your inventory while it cleared, or because you had non-Amazon channels into that state), file the return and pay the tax owed. Penalties for late returns are usually waivable if you respond promptly. Penalties for ignoring notices are not.
If the situation is complex (multiple states, multiple periods, contested nexus), get a sales tax specialist involved before you talk to the state. The conversations move faster and cost less when someone who knows the trailing rules is doing the talking.
The lesson, simply
Leaving a marketplace is not just an operational decision. It’s a tax compliance event. Plan it like one.
The sellers who pull out of Amazon, Walmart, or any marketplace cleanly are the ones who treated the inventory move as the start of a six-to-twelve-month wind-down, not the end. The ones who treat it as a clean break are the ones I hear from in spring.
