OSS/IOSS VAT for e-commerce 2026: marketplaces, channel margin and e-reporting

E-commerce accountant 2026: OSS/IOSS VAT, marketplaces, channel margin and e-reporting#

Short answer. A 2026 e-commerce accountant goes well beyond producing the year-end accounts. They secure your Shopify, Amazon, PrestaShop, Stripe and marketplace flows, apply OSS/IOSS VAT country by country (not at an average rate), rebuild your net margin by channel and frame B2B e-invoicing and B2C e-reporting. This guide is the operational method we apply at our firm on roughly thirty e-commerce files, from a 200 k€/year DTC Shopify to an 8 m€/year multi-marketplace international operator.

1. Why a dedicated e-commerce guide in 2026
2. Stack and data flows: Shopify, Prestashop, Amazon, marketplaces
3. Stripe / PayPal / Adyen reconciliation: the 2026 J+10 method
4. OSS/IOSS VAT: rules, thresholds, EU country rates
5. Amazon FBA pan-EU: stock and registrations
6. Marketplaces: who collects VAT in 2026
7. Returns, refunds and provisions
8. E-invoicing and e-reporting: 2026/2027 schedule
9. J+10 monthly closing checklist
10. Net channel margin: the calculation method
11. Common mistakes by non-specialised firms
12. When to switch to a specialised e-commerce CPA

The French e-commerce market reached 196.4 b€ in 2025 (Fevad), with 3.2 billion transactions and a 62 € average basket. Volumes have shifted, but the accounting toolkit of most e-commerce SMEs has stayed generalist: average VAT rate, gross Stripe payouts, gross back-office margin used as the real one.

Three structural shifts make a specialised approach mandatory in 2026:

• OSS / IOSS: cross-border B2C EU sales must be taxed at the country-of-consumption rate above 10 000 €/year cumulated. The "average rate" logic is no longer defensible.
• E-invoicing: B2B e-invoice reception becomes mandatory on 1 September 2026. B2B issuance and B2C e-reporting follow by 1 September 2027 for SMEs.
• Marketplaces: Amazon, eBay, Cdiscount, TikTok Shop, Etsy partially collect VAT in some scenarios (deemed supplier). The exact role depends on the flow and requires a platform report audit.

The silent risk is to look compliant on paper but build everything on misclassified data: wrong country, marketplace responsibility, foreign stock, unallocated refunds. At audit, these gaps translate into VAT recapture and late interest.

A reliable e-commerce ledger relies on a clear separation between the storefront, the analytical layer and the legal accounting hub.

The frequent mistake is to confuse the platform with the legal hub. Shopify is not an accounting tool. Amazon Seller Central is not a journal. Without a connected legal hub, you cannot produce a defensible balance sheet nor a properly split OSS VAT return.

A Stripe payout aggregates: gross revenue, PSP fees (≈ 1.4 % + 0.25 € in Europe), refunds, chargebacks, dispute fees, rebillings. Without a triangular reconciliation order / PSP / bank, you cannot justify your net revenue, fees, chargebacks or returns.

Our cabinet method, J+1 to J+10:

1. Shopify orders + taxes export — J+3
2. Stripe Payments + Balance + Disputes export — J+3
3. Triangular reconciliation order / PSP / bank — J+5
4. Identification of fee, refund, chargeback, dispute fee, holdback — J+5
5. OSS/IOSS country-of-consumption split — J+7
6. Closing entries and corrections — J+9
7. Founder review: net channel margin, threshold alerts — J+10

Above 500 orders/month or 2 PSPs combined, this process does not hold without automation. The analytical layer (Sqalie) or a Pennylane middleware becomes mandatory.

4.1 The 10 000 € OSS threshold#

CGI article 259 D: for a French seller, a single 10 000 € threshold applies to the annual cumulated cross-border B2C EU sales (excl. France). Below, you charge French VAT. Above, the consumer's country rate applies on each sale, and you declare via the OSS one-stop shop.

4.2 EU 2026 standard rates (TEDB, European Commission)#

Standard rates 2026: LU 17 %, MT 18 %, DE 19 %, CY 19 %, AT 20 %, BG 20 %, FR 20 %, BE 21 %, CZ 21 %, ES 21 %, LT 21 %, LV 21 %, NL 21 %, RO 21 %, IT 22 %, SI 22 %, IE 23 %, PL 23 %, PT 23 %, SK 23 %, EE 24 %, EL 24 %, DK 25 %, HR 25 %, SE 25 %, FI 25.5 %, HU 27 %.

A reduced rate can apply to certain products (books, food, press, some services) with country-specific rules. Our OSS/IOSS VAT simulator prefills these 27 rates and allows a custom rate per line.

4.3 IOSS and low-value imports#

IOSS applies to distance sales of imported goods ≤ 150 € per parcel to an EU consumer. The threshold is per parcel, not per total order. Above 150 €, the standard customs route applies with import VAT and duties.

Amazon FBA Pan-EU moves your stock between fulfilment centres in Germany, France, Italy, Spain, Poland and Czechia to optimise lead times. Tax consequence: you may become liable for VAT in each country, outside OSS.

Practical case:

• Sale to France from German stock: intra-EU stock transfer taxed in Germany, DE VAT registration required, local FR delivery taxed in France.
• Sale to Poland from Polish stock: domestic Polish sale, PL VAT registration required.

The Amazon VAT Transactions Report lists every stock movement (transfer, return, sale). It is the source of truth.

The deemed supplier status applies in two main scenarios from the 2021 EU VAT e-commerce package:

1. B2C imported sale ≤ 150 € facilitated by a marketplace: the marketplace collects VAT at the sale.
2. Intra-EU B2C sale by a non-EU established seller facilitated by a marketplace: the marketplace collects VAT at the country-of-consumption rate.

For most intra-EU sales between EU sellers and EU buyers, the seller remains liable. Audit each platform report (Amazon VAT Transactions Report, eBay, Cdiscount, TikTok Shop, Etsy) to identify exactly who collects.

A return is not just a cancelled sale. It generates: a VAT correction, a stock movement, a return shipping cost and possibly a write-off. In fashion and beauty, return rates typically reach 8 to 25 %. Failing to provision properly creates a scissors effect: VAT collected is paid to the State before refund credit notes are recorded.

The French reform (ordinance 2021-1190 and amending decree 2024) splits two flows:

• E-invoicing: B2B invoices between French taxable persons, sent through a PDP in structured format (Factur-X, UBL, CII).
• E-reporting: transmission to the tax authority of B2C transactional data, international B2B and certain exempt operations.

Consolidated schedule:

For a pure B2C e-commerce, the priority is e-reporting of transactional data.

J+1 to J+3 — Data prep: order exports, PSP exports, Amazon VAT Transactions Report, ad receipts. J+4 to J+5 — Reconciliation: triangular order/PSP/bank, fees, refunds, chargebacks, country-of-consumption split. J+6 to J+7 — VAT and stock: OSS country by country, IOSS flows, multi-warehouse inventory, return provisions. J+8 to J+9 — Accounting and reporting: journal entries, channel margin, cash, threshold alerts. J+10 — Founder review: P&L, channel margin, decisions on ads, stock, registrations.

Net channel margin = HT revenue − COGS − PSP fees − marketplace fees − shipping/3PL − returns − attributed ads − unrecoverable VAT

Typical Shopify DTC: 36 % net margin. Typical Amazon FBA: 33 % net margin. The 8 to 12 point gap between channels guides ad budget allocation — not the gross margin.

Recurring patterns we find when taking over files: average VAT rate, gross Stripe entries, OSS threshold crossed without effective switch, FBA Pan-EU activated without local registrations, 20 % shipping fees on 5.5 % products, discontinuous invoice numbering, no return provision, gross margin used as net margin, no by-channel reading.

Triggers: revenue > 300 000 €/year with active EU sales, several channels (DTC + Amazon or multi-marketplace), 2+ PSPs, multi-warehouse stock, return rate > 5 %, > 500 orders/month, ad decisions taken without net channel margin.

For a French seller, CGI article 259 D sets a single 10 000 € threshold that applies to your annual cumulated cross-border B2C EU sales (France excluded). Below that line, every sale to an EU consumer carries French VAT. Once the cumulated total clears 10 000 €, the consumer's country rate applies on each sale, and you report the whole set through the OSS one-stop shop on impots.gouv.fr. The point most generalist setups miss is that this is one combined ceiling across all member states, not a per-country allowance.

What the threshold does not include matters just as much as what it includes. It excludes your French domestic sales, your intra-EU B2B sales (which are reverse-charged by the buyer who holds a valid EU VAT number), and any sales collected by a marketplace that is treated as the deemed supplier. Folding those flows into the count is a common error that pushes a seller to register early, or worse, masks the moment they truly cross the line.

In practice, three questions answer most threshold doubts. First, do you have to register with OSS from the first euro of EU sales? No. As long as the cumulated annual cross-border B2C EU total stays under 10 000 €, you charge French VAT. Above it, OSS becomes the practical option to avoid registering country by country. Second, can you opt in below the threshold? Yes. The OSS option is open before you reach 10 000 €, and it can simplify your organisation if you already know you will cross the line within the year. Third, what if you forgot to switch last year? A voluntary correction is possible, and the faster and better documented it is, the lower the penalties. The cost of a clean correction is usually far below the cost of an audit you did not choose.

A worked example shows why the country rate is not a rounding detail. On a B2C sale of 100 € excluding VAT to Germany, where the standard rate is 19 %, you invoice 119 € including VAT and remit 19 € through OSS. The same sale to Hungary, at 27 %, invoices at 127 € including VAT and remits 27 €. Across a mixed EU volume, the margin gap between destination countries can reach 8 points excluding VAT, which is invisible the moment you collapse everything into a single average rate. A reduced rate can also apply to certain products such as books, food, press or some services, with rules that differ by country, so a per-line treatment is safer than a blanket assumption.

IOSS is a separate regime and should not be confused with OSS. It applies to distance sales of imported goods of 150 € or less per parcel sold to an EU consumer. The decisive nuance is that the 150 € ceiling is assessed per parcel, not per overall order. A customer placing one order that ships in two parcels is judged parcel by parcel, and a single parcel above 150 € falls out of IOSS entirely and follows the standard customs route, with import VAT and duties applied at the border.

Registering for IOSS lets you collect VAT at the point of sale, clear the goods quickly through customs and avoid double taxation, where the customer would otherwise be charged again on delivery. The operational catch is that the IOSS identifier must be transmitted correctly to the carrier. An identifier that never reaches the freight or postal operator means the parcel is treated as if no VAT had been collected, and the customer is billed a second time on arrival, which generates refused deliveries and refund requests. Getting the data handoff right is therefore as important as holding the registration itself.

Since the 2021 EU VAT e-commerce package, a marketplace can be treated as the deemed supplier, meaning it becomes liable for collecting the VAT rather than the seller. Two main scenarios trigger this. First, a B2C imported sale of 150 € or less facilitated by a marketplace: the marketplace is liable for the VAT collected at the sale. Second, an intra-EU B2C sale by a seller established outside the EU and facilitated by a marketplace: the marketplace is liable for the VAT of the country of consumption.

Outside those two cases, the rule is the one sellers most often get wrong. For most intra-EU sales between an EU-established seller and an EU buyer, the seller remains liable, and the marketplace's role is limited to intermediation against a commission. So a French seller shipping within the EU generally still owns the VAT obligation, even when the order came through Amazon, eBay or another platform. Assuming the platform handles everything is exactly how an OSS threshold gets crossed without anyone declaring it.

Because the answer depends on the flow, the only reliable approach is to audit the platform report itself rather than rely on a general impression. Each platform exposes the information differently: on Amazon, the VAT Transactions Report carries a tax reporting scheme field distinguishing deemed reseller from non-deemed; eBay shows it through VAT invoices and the Tax tab as marketplace facilitator versus seller; Cdiscount states platform collection in its monthly VAT report; TikTok Shop uses a Tax Settlement Report; and Etsy a Tax Settlement marked as marketplace facilitator. Reading the right field per platform is what separates a defensible return from a guess.

Amazon FBA Pan-EU moves your stock between fulfilment centres in Germany, France, Italy, Spain, Poland and Czechia to shorten delivery times. The tax consequence is direct and frequently overlooked: you can become liable for VAT in each of those countries, and these obligations sit outside the OSS one-stop shop. OSS covers cross-border sales to consumers, not the domestic registrations triggered by holding and shipping stock locally.

A few concrete flows illustrate the exposure. A sale to France from German stock is an intra-EU stock transfer taxed in Germany, requiring a German VAT registration, with the local French delivery then taxed in France. A sale to Poland from Polish stock is a domestic Polish sale that requires a Polish VAT registration. A sale to Italy from German stock, shipped to Italy, depends on the conditions: it can be a transfer plus an intra-EU sale routed through OSS where the conditions are met, or it can require a local registration. The Amazon VAT Transactions Report lists every stock movement, whether transfer, return or sale, and it is the source of truth to work from rather than the seller dashboard.

Our recommendation is cautious by design. Activating Pan-EU without support exposes you to a simultaneous regularisation across four or five countries, which is far more costly to unwind than to set up correctly. Either keep Pan-EU switched off until the framework is scoped, or activate it alongside an e-commerce accountant and a provider of EU VAT registrations. On the cost question, registrations through specialist providers typically run from 600 to 1 200 € excluding VAT to set up, then 60 to 150 € excluding VAT per monthly or quarterly filing. That outlay is justified when you generate several tens of thousands of euros of local sales from local stock, which is precisely the Pan-EU pattern, and hard to justify before it.

For a scoping audit, contact our e-commerce CPA practice or use our OSS/IOSS VAT simulator.