A Canadian Amazon FBA Seller's US Taxes: What the Warehouse Inventory Does and Doesn't Change

The Canadian FBA seller's tax anxiety is usually pointed at the wrong layer, because the three layers moved in different directions over the past decade. Sales tax, the historic terror, mostly resolved itself: marketplace facilitator laws in essentially every sales-tax state make Amazon the collector and remitter on marketplace sales — the seller's own registration obligations now concentrate on off-marketplace channels (the Shopify store runs the ordinary economic-nexus threshold analysis) and on the handful of state-specific registration or reporting quirks that survive for marketplace sellers with in-state inventory; the blanket register-in-every-FBA-state advice of the 2010s is obsolete, and unwinding legacy registrations is its own small project. Income tax, federal: the analysis is the treaty's — business profits are taxable in the US only through a permanent establishment, and the FBA question is whether inventory sitting in Amazon's warehouses, fulfilled by Amazon as an independent operator, constitutes a fixed place of business of the seller. The treaty's own architecture points helpfully: facilities used solely for storage and delivery of the enterprise's goods sit in the preparatory-and-auxiliary exclusions, and a third party's warehouse is not naturally the seller's fixed place — the position that inventory-in-FBA alone does not create a PE is the mainstream professional view — but the question carries genuine debate at the edges (scale, additional US activities, the seller's own personnel or facilities), and the IRS's view of aggressive fact patterns is not guaranteed to match the seller's forum. The posture that resolves the uncertainty is the protective Form 1120-F (or the individual's protective 1040-NR) with the treaty-based disclosure: filed on time, it asserts the no-PE position, starts the limitation clock, and — the decisive feature — preserves the right to deductions if the position ever loses, without which a losing seller is taxed on gross receipts; for a business with FBA-scale US revenue the protective filing is cheap insurance with no sensible alternative. Income tax, state: states aren't treaty parties, and FBA inventory is physical presence — a few states assert income or franchise tax jurisdiction over inventory-nexus sellers where the federal solicitation protection doesn't apply to the fact pattern; the exposure is state-by-state, usually modest at small-seller scale, and belongs on the annual review rather than in the panic folder. Around the three layers sit the operating items: the seller's Canadian side is unchanged (worldwide income on the T2 or T1, GST/HST zero-rating analysis on exports, the US-entity question answered by the entity-selection framework — most Canadian FBA sellers correctly run their Canadian corporation or proprietorship with no US entity at all); Form W-8BEN-E or W-8BEN sits in Amazon's tax interview so platform payments flow without backup withholding; import duties and customs on inventory entering the US run their own track; and the seller's records — inventory by state, revenue by channel, the day-log of any US trips — feed every layer's annual review.

Key takeaways

• Sales tax is mostly Amazon's job now: marketplace facilitator laws put collection on the platform for marketplace sales; the seller's own analysis covers off-marketplace channels against economic-nexus thresholds and the residual state quirks — and cleans up legacy registrations that no longer serve.
• Federal income tax runs on the PE question: third-party fulfillment inventory alone, under the storage-and-delivery exclusions and the not-your-fixed-place logic, supports the mainstream no-PE position — held honestly, with awareness that edge fact patterns (US staff, owned facilities, heavy US presence) change it.
• The protective return is the professional posture: timely 1120-F/1040-NR with the treaty disclosure asserts the position, starts the clock, and preserves deductions against the downside — the filing that converts a debated question into a managed one.
• States run their own nexus: inventory is presence; a few states' income/franchise regimes reach it; the exposure is reviewed annually, state by state, in proportion to the numbers.
• The Canadian side doesn't move: worldwide income taxed at home, exports zero-rated with the substantiation file, no US entity needed for the standard structure — the LLC a US forum recommended remains the one thing not to do.
• Platform paperwork is real paperwork: the W-8 in Amazon's tax interview (refreshed on cycle), the 1099-K's irrelevance-but-arrival for some sellers, and records by state and channel — the administrative spine every layer's review reads from.

The FBA seller's annual review

One sitting, four questions: revenue by channel and state (marketplace versus direct — the direct channel's economic-nexus sweep runs here); the PE fact pattern (any new US activities, people, facilities, or trips that move the analysis — and the day-log that proves the absence); the protective filing (prepared, disclosed, filed on time, every year the US revenue is meaningful); and the state income-tax screen (inventory states against their regimes, materiality-weighted). Add the Canadian export file check and the W-8 expiry glance, and the whole review runs two hours a year — the entire tax overhead of a structure the forums describe as a minefield.

Worked example

A London, Ontario supplements brand sells US$2.1 million a year: US$1.7M through Amazon US with FBA inventory across a dozen states, US$400,000 through its own Shopify site. Sales tax: Amazon collects and remits on the marketplace revenue under facilitator laws; the Shopify channel's economic-nexus sweep shows four states over threshold — registrations and engine-collection for those four, and two legacy registrations from 2019-era advice are formally closed. Federal income tax: no US entity, no US staff, two trade-show trips logged; the no-PE position rests on the third-party-fulfillment analysis; the corporation's protective 1120-F with Form 8833 files by deadline as it has for three years, deductions preserved against a position the owner understands is strong-but-debated. State income tax: the annual screen flags one inventory state whose franchise-tax minimum plausibly applies — a US$800 filing decision taken on materiality rather than principle. Canadian side: the T2 reports everything; US-bound export sales zero-rate with the shipping file; the W-8BEN-E in Amazon's interview renews on schedule. Total US tax paid: state trivia. Total protection: a protective return, a day-log, and a two-hour review — which is what the mainstream position looks like when it's papered instead of posted about.

Official sources

"The business profits of a resident of a Contracting State shall be taxable only in that State unless the resident carries on business in the other Contracting State through a permanent establishment situated therein." — Canada-United States Tax Convention, Article VII, https://www.canada.ca/en/department-finance/programs/tax-policy/tax-treaties/country/united-states-america-convention-consolidated-1980-1983-1984-1995-1997.html

"A foreign corporation files this form to report their income, gains, losses, deductions, credits, and to figure their U.S. income tax liability." It also transmits treaty-based return positions (Form 8833) and calculates the branch profits tax. — Internal Revenue Service, About Form 1120-F, https://www.irs.gov/forms-pubs/about-form-1120-f

Practitioner note

FBA tax panic is five years out of date in one direction and five years naive in the other: the sales-tax layer largely became Amazon's problem, while the income-tax layer became a real treaty position that deserves real paper. Our FBA files hold three things — the no-PE fact pattern with its day-log, the protective return filed every year on time, and the channel-by-state revenue sweep — and the sellers who maintain them spend less on all of it annually than the forums spend on one bad registration spree.

See also: For whether you charge GST/HST to US clients, see whether you charge GST/HST to US clients; and browse every cross-border tax topic guide, organized by situation.

Next step

Fairlight prepares the FBA seller's US tax program — the PE position and protective 1120-F/8833 filings, the marketplace-versus-direct sales tax sweep with legacy cleanup, state income screens, and the Canadian export and platform paperwork file. See cross-border pricing or book a call.