You open your FBA shipment report and see that units you sent to Kentucky are now sitting in three other states. You never approved that move. Yet each of those warehouse locations can quietly create an Amazon FBA sales tax nexus, meaning a legal connection that gives a state the right to tax your business. Most sellers find out years later, usually in a letter demanding back taxes and penalties.
This is one of the most misunderstood parts of US sales tax for Amazon sellers. Amazon collects tax on marketplace orders, so the risk feels handled. It usually is not. A firm like AMZ Accountant spends its days untangling exactly this gap for eCommerce operators, because proactive tax planning is far cheaper than reacting to a state audit.
Keep reading to learn how physical and economic nexus differ, why FBA inventory placement makes this harder for Amazon sellers than for anyone else, and how to pull the exact reports that show where your stock has lived.
The Two Nexus Triggers FBA Sellers Must Separate
Two separate doors lead into a state’s tax system, and FBA sellers often walk through both without noticing. Mixing them up can turn a $500 registration into a five-figure back-tax bill.
Physical Nexus: When Stored Inventory Creates a State Connection
Physical nexus means you have something tangible in a state: an office, an employee, or goods. For FBA sellers, the goods part is the trap. Your inventory sitting on a shelf in a fulfillment center is your property, in their state.
States have treated warehoused inventory as physical presence for decades. It predates online selling entirely. That is why a seller in Florida can owe filings in Pennsylvania without ever visiting, and there is no safe minimum quantity you can point to.
Economic Nexus: When Sales or Transactions Cross a State Threshold
Economic nexus is about money, not goods. Cross a state’s sales dollar figure, and you owe obligations there even with zero inventory in that state.
Most states use a $100,000 sales threshold. Some still count 200 transactions, though more states drop that second test each year. A few sit higher: Texas uses $500,000, which keeps smaller sellers out of scope.
Two details catch sellers off guard:
- Many states count your gross sales toward the threshold, including Amazon orders where Amazon already collected the tax
- Combined revenue across Amazon, Shopify, Walmart, eBay, and Etsy usually counts together, not channel by channel
Why Wayfair Did Not Replace Inventory-Based Nexus
The 2018 South Dakota v. Wayfair decision added economic nexus. It did not remove physical nexus. Sellers routinely assume the newer rule replaced the older one, and that assumption is expensive.
You can trigger obligations in a state where you sold $2,000 and stored 40 units. Here, stored inventory alone triggered the obligation, independent of how little revenue came with it. Roughly 30 states host Amazon fulfillment centers, so the inventory path is often wider than the revenue path.
The real question is where your units have actually traveled, and that answer lives inside Amazon’s own placement decisions.
Why Amazon Inventory Placement Creates Hidden State Exposure
Amazon can spread a single 300-unit shipment across a dozen states within weeks. You don’t get a notice, and you don’t get a vote. That silent redistribution is what separates FBA from every other fulfillment model.
How Amazon Fulfillment Centers and Rebalancing Affect Inventory Location
You ship to one receiving center. Amazon then rebalances stock toward buyers to protect Prime delivery speeds. A holiday demand spike in the Northeast can pull your units into Massachusetts or Maine overnight.
Compare that to a single 3PL warehouse. There, you know your inventory location because you chose it, and your exposure stays in one state. With FBA, your physical footprint changes based on Amazon’s forecasting model, not your plan.
The Inventory Trap: Why a Small Amount of Stock Can Matter
The math is unkind here. A state does not care whether you held 5,000 units or 8. Once inventory is present, registration and filing duties can attach, and unfiled returns build penalties month after month.
Some states go further than sales tax. A 2025 California Office of Tax Appeals ruling confirmed that storing FBA inventory worth less than $2,500 was enough, on its own, to make an out-of-state seller “doing business” in California for franchise and income tax purposes, regardless of whether the state’s economic nexus thresholds were ever met.
California’s LLC franchise tax is $800 a year, and states may also argue income tax exposure, purely because your goods lived there. On a product line clearing $40,000 in annual profit, one state’s back taxes plus interest can erase a full quarter of margin.
FBA Inventory Placement Service Does Not Eliminate Monitoring Duties
Paying inventory placement fees to send stock to fewer locations narrows your footprint. It does not lock it. Amazon still redistributes after receipt, and your obligation follows the units.
That means monitoring is not optional, no matter which placement option you pay for. The good news is that Amazon hands you the data, once you know which report to open.
Amazon Collects Marketplace Tax, but Your Duties Continue
Amazon collects and remits sales tax on marketplace orders in every state with sales tax. That solves the collection problem. It does not solve your registration or filing problem.
What Marketplace Facilitator Laws Cover on Amazon Orders
Marketplace facilitator laws make Amazon responsible for collecting sales tax on sales through its marketplace. Amazon calls this Marketplace Tax Collection. Amazon charges the tax at checkout, and it never touches your payout.
These laws cover sales tax and certain regulatory fees on Amazon orders only. They do not cover income tax, franchise tax, or gross receipts tax created by your inventory being in a state.
Where Registration and Return Filing May Still Apply
Many states still want you registered and filing, even when Amazon remits every dollar. You report gross sales and claim a marketplace deduction, or file a zero return showing nothing due from you.
States want visibility into who is selling into their borders. Skipping those filings is what invites an audit, not the tax itself.
Why Shopify, Direct Sales, and Other Channels Compound Exposure
Here is where the bill grows. On your own Shopify or WooCommerce store, you are the seller of record, so collection and remittance are yours. Walmart Marketplace, eBay, and Etsy are covered by facilitator rules; your website is not.
Multi-channel sellers face a stacked problem:
- Amazon inventory creates the physical connection in a state
- Combined revenue across all channels pushes you past economic thresholds
- Only your direct sales require you to actually collect the tax yourself
A Shopify store doing $60,000 into a nexus state, with no tax collected, means that tax comes out of profit you already spent. Time to find out exactly which states apply to you.
How to Map Your Nexus Footprint in Seller Central
Amazon gives you the inventory history for free. Two Seller Central reports answer the question most sellers pay consultants to guess at.
Pull the FBA Inventory Ledger and Inventory Event Detail Report
Go to Seller Central, then Reports, then Fulfillment. Download the FBA Inventory Ledger in Detail view. This report, once called the Inventory Event Detail report, tracks every receipt, transfer, and removal.
Set the date range as far back as Amazon allows, then export to a spreadsheet. Older history matters because exposure starts the day inventory arrives, not the day you notice.
Use Fulfillment Center IDs to Reconstruct Inventory History
Each row carries a fulfillment-center-id, a short code like ONT8 or BNA3. The letters map to an airport or city, which maps to a state. Build a simple lookup column matching each code to its state.
Then pivot by state and month. You now have a dated record of every state where your goods were stored, which is exactly what a state auditor would reconstruct.
Build a Recurring Nexus Monitoring Process
Do this monthly, not yearly. Amazon’s placement changes with demand, so a new state can appear in any given month. Sales tax automation tools such as TaxJar or Avalara can track thresholds and inventory states automatically once volume justifies the subscription fee.
Once you’ve built your map, the next decision is where registration is genuinely worth doing.
What Registration, Filing, and Remittance Require
Registering in all 30 inventory states means 30+ returns to file, plus software fees. Most sellers under $2 million serve their margins better with a risk-based approach.
Decide Where a Sales Tax Permit Is Required
Register first where the risk is highest and clearest:
- Your home state, always, since that is where you operate
- Any state where you crossed the economic nexus threshold
- States holding meaningful inventory that enforce aggressively, such as California, Washington, and Illinois
Sellers with light inventory in lenient states often defer, with CPA input. That is a judgment call about cost versus risk that deserves professional input.
Set Up Collection Rules for Taxable Non-Marketplace Sales
After a permit is issued, set collection rules on your own storefront for that state. Product taxability varies: supplements, apparel, and food are treated differently from state to state, and getting it wrong means you either shorted the state or overcharged buyers.
Overcollection is real money too. Sellers frequently recover thousands in tax charged where nothing was owed once someone reviews the setup.
File on Time Even When the Return Is Zero
States assign filing frequency: monthly, quarterly, or annually. Missing a zero return still triggers penalties, often $50 to a few hundred dollars, plus the risk of losing your permit.
Registration going forward is the easy part. Handling the years already behind you takes a different plan.
Address Past Exposure and Build a Proactive Plan
If inventory sat in a state for three years with no filings, registering today can flag those open periods. That is why the order of operations matters more than speed.
Assess Historical Inventory and Multi-Channel Sales Before Registering
Start with the inventory ledger history and your channel-by-channel revenue by state. Then quantify the actual exposure: uncollected tax on direct sales, plus penalties, plus any income or franchise tax question.
Most FBA-only sellers find the real liability is small, because Amazon already remitted the tax. The bigger numbers usually come from a Shopify store that never collected anything.
When a Voluntary Disclosure Agreement May Help
A voluntary disclosure agreement, or VDA, is a deal you make with a state before it finds you. States typically waive penalties and shorten the lookback period in exchange for coming forward and paying back taxes owed.
VDAs work best when exposure is real and material. For a seller facing $18,000 in uncollected tax, penalty relief alone can save several thousand dollars.
Use Better Records to Support Sales Tax and Income Tax Decisions
Clean books make all of this cheaper. State-level sales data, accurate COGS, and reconciled Amazon fees also support your 1099-K reporting and your federal return.
That same record set is what makes forward-looking tax planning possible instead of reactive filing.
Frequently Asked Questions
Does Storing Inventory in Amazon FBA Warehouses Create Sales Tax Nexus?
Yes, in most states. Inventory you own sitting in a fulfillment center counts as physical presence, even if you never visited that state. No reliable minimum quantity keeps you safe.
Which States Require Amazon FBA Sellers to Register for Sales Tax?
It depends on where your inventory sits and where your combined sales cross thresholds. Your home state is always first. California, Washington, and Illinois enforce inventory-based nexus most aggressively.
How Can I Find Out Where Amazon Stores My FBA Inventory?
Download the FBA Inventory Ledger from Reports, then Fulfillment in Seller Central. Match each fulfillment-center-id to its state and pivot by state to see your full footprint.
What Sales Tax Obligations Apply When Amazon Moves Inventory Between States?
Obligations can attach in the new state from the day your units arrive. Amazon does not notify you, so monthly ledger reviews are the only practical way to catch a new state early.
Does Amazon Collect and Remit Sales Tax for FBA Sellers in Every State?
Amazon collects and remits sales tax on marketplace orders in every state with a sales tax. That does not cover your Shopify or wholesale sales, and many states still require you to register and file.
What Happens if an Amazon Seller Has Unfiled Sales Tax Returns in Nexus States?
Penalties and interest accrue per period, and states can assess estimated liabilities. A voluntary disclosure agreement often reduces penalties and limits how far back the state can look.
Turn Inventory Data Into Tax Certainty
Your sales tax exposure is not a mystery. It is sitting in a Seller Central report, waiting to be sorted by state. Sellers who pull that data monthly make calm, cheap decisions. Sellers who wait get a letter and a deadline.
Get your registrations right, file the zero returns, and stop letting Shopify sales create tax you pay out of pocket. That is money staying in your margin.
Not sure if your current setup is costing you money? AMZ Accountant offers a free consultation for eCommerce sellers, no obligation required. Book a 15-minute strategy call and see where your numbers actually stand.