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