E-commerce & Amazon FBA: US Nexus, Sales Tax & Customs EIN Architecture (2026)

Inventory creates nexus, not your formation state

Amazon FBA places your units in fulfillment centers you do not control. Those buildings are physical presence. Marketplace facilitator statutes mean Amazon often collects sales tax at checkout, which is a relief, not a complete tax system. You still need an importer-of-record identity, an EIN, customs bonds or broker instructions, income-tax analysis in the US and at home, and a company that can sign Amazon’s tax interview. A merchant of record such as Paddle will not take physical goods. The rails matcher will mark Paddle and LemonSqueezy not feasible for ecommerce; believe it.

Most international sellers still form a Wyoming LLC because the annual report is $62 and the statute is well understood, then they discover California, Texas, or New Jersey warehouse facts anyway. Formation state ≠ nexus state. Run the high-volume Wyoming FBA scenario: $62 + $100 + $2,800 bookkeeping + $800 CPA = $3,762 before sales-tax software and inventory accounting.

EIN, customs, and Form 5472

Brokers want an EIN. Foreign owners obtain one with Form SS-4 without an SSN. Amazon wants a W-8 or W-9 that matches the legal name on the seller account. A foreign-owned single-member LLC still files Form 5472 and a pro-forma Form 1120. High volume does not create a new form; it creates more reportable related-party transactions (inventory purchases from the owner, working-capital advances, unpaid “loans”). Keep a ledger that a CPA can actually audit.

First-party setup through Firstbase is the usual way to combine state formation, registered agent, and EIN. USD receipts then sit in Mercury. Supplier payments in CNY, EUR, or GBP sit on Wise. None of those partners files your 5472.

Sales tax, product tax codes, and marketplaces

Even with facilitator collection you must map product taxability, marketplace versus off-Amazon stores, and any states where you sell on your own Shopify domain. A second channel without Amazon’s facilitator protection can require registration immediately. Economic nexus thresholds (revenue or transaction counts) still exist for your own site. Budget software and a US sales-tax specialist; do not ask a formation clerk to opine on clothing versus dietary supplements.

Why Delaware is usually the wrong FBA default

FBA sellers rarely need preferred stock in year one. They need cheap maintenance, a bank account, and clean books. Delaware’s $400–$1,200 franchise tax and Form 1120 C-Corp model are for venture studios, not supplement brands. Read Wyoming LLC vs Delaware C-Corp if a buyer later wants a C-Corp. Until then, stop paying for Chancery theater.

SaaS tools sold next to the brand (subscription boxes with software upsells) should isolate digital MoR revenue using the SaaS and AI guide so you do not pollute a Paddle account with physical SKUs. UAE or UK personal moves do not erase FBA nexus; see UAE Free Zone vs US LLC and UK LTD vs US LLC.

Worked example

A Shenzhen operator selling home goods through FBA, $600k revenue, high shipment volume, non-US single member. Wyoming LLC, Mercury, Wise suppliers, Firstbase formation. Books must track landed cost, Amazon disbursements, storage fees, and owner advances. Form 5472 is mandatory. Paddle is not a solution. If the operator later relocates to Dubai, the warehouses in Kentucky are still there. If they add a UK LTD for European retail, they have a group and need intercompany terms. The simulator will price the US compliance line; it will not price freight.

Agencies running stores for clients should keep client inventory out of the agency’s EIN. That operational split is also covered in the remote agency guide.

Landed cost, inventory accounting, and cash

High transaction volume is why the simulator’s bookkeeping line jumps to $2,800. You are not paying for data entry theater; you are paying someone to reconstruct Amazon settlement reports, storage fees, returns, and reimbursements into inventory and COGS. If you cannot tell contribution margin by SKU, you cannot tell whether a 9% UAE rate or a 0% Wyoming state rate matters. Cash trapped in inbound containers is not profit. Neither is a reimbursed reimbursement you already booked as income.

Customs classifications (HTS) affect duty and, sometimes, whether a product can enter at all. The EIN identifies the importer; it does not pick the code. Brokers will guess if you do not instruct them. Wrong codes create retroactive bills. Keep a SKU-to-HTS table next to your operating agreement. When you add a UK or EU channel, you are repeating this work with different forms, which is why some sellers open a UK LTD as a regional importer rather than stretching the Wyoming company into HMRC. That is an operations decision described in UK LTD vs US LLC, not a patriotism decision.

Do not mix FBA inventory with a creator merch drop in the same legal entity if the merch is a hobby and the FBA line is a real company. Losses, sales-tax codes, and bank risk models differ. Split when the books would lie if you kept them together. The formation vendor will not warn you; the simulator will only show the US compliance floor.

Editorial disclaimer (E-E-A-T)

This page is planning output from FoxyCorp research. It is not legal, tax, or accounting advice. Confirm filings, residency, substance, and banking eligibility with a licensed attorney or certified public accountant in each relevant jurisdiction before you incorporate, open accounts, or file returns.