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Amazon FBA

Specialised Amazon FBA Accounting and Margin Analysis

13 min read2026-05-08 Reviewed by specialist accountant

Amazon FBA is the largest single channel for many UK e-commerce brands and the most operationally distinct. Settlement reports are bi-weekly and combine 20+ fee types per cycle. PPC advertising spend is reconciled separately from product revenue. Commingled inventory creates accounting complexity around lost or damaged stock. The Amazon VAT Calculation Service offers seller-side automation that has trade-offs. Account-level reserves can lock up tens of thousands of pounds during holiday season. And the difference between Seller Central and Vendor Central is fundamental — different revenue model, different accounting.

This pillar covers the FBA-specific accounting issues. Each section links to a detailed companion piece.

Generic e-commerce accounting under-handles FBA

Settlement reports require specialist tools (A2X, Link My Books, SellerLegend) to decompose into journal entries. Manual treatment under-reports fees, miscategorises reserves, and produces unreliable margin numbers.

Decoding the Amazon settlement report

A typical Amazon settlement report includes these line categories:

  • Product revenue (sales price × units).
  • Promotional discounts.
  • Shipping revenue (where applicable).
  • Referral fee (Amazon's percentage of sales price; 8-15% typically).
  • FBA fulfilment fee (per unit, varies by size/weight).
  • Monthly storage fee.
  • Long-term storage fee (for slow-moving stock 365+ days).
  • Returns and refunds.
  • Reimbursements for lost/damaged inventory.
  • PPC advertising charges (separate stream usually).
  • Reserves held back.
  • Net payout.

PPC and ROAS reconciliation

Amazon advertising spend is charged to the seller separately from product sales reconciliation. Reconciliation steps:

  1. 1Pull the advertising spend report from Amazon Ads.
  2. 2Match each campaign to the product family it promotes.
  3. 3Calculate ROAS (Return on Ad Spend): attributed sales / ad spend.
  4. 4Calculate true profitability: ROAS × gross margin - 1; the advertising must produce more incremental margin than the spend cost.
  5. 5Many products show positive ROAS but negative incremental contribution because the gross margin is too low to support the spend.

Commingled inventory and reimbursements

Amazon's default fulfilment model commingles inventory across sellers (units carrying the same FNSKU are interchangeable). When inventory is lost or damaged, Amazon reimburses based on average selling price. Sellers must track:

  • Inbound shipments and Amazon-confirmed receipts.
  • Inventory ledger changes (positive and negative).
  • Reimbursement notifications and amounts.
  • Discrepancies for claim where reimbursements appear missing.

For active sellers, reimbursement claims are a routine activity that recovers thousands per year. Specialist services (Refunds Manager, GETIDA, Carbon6) automate the claim process.

The Amazon VAT Calculation Service (VCS)

VCS lets Amazon calculate and apply UK/EU VAT on the seller's behalf. Pros: simplifies multi-jurisdiction VAT for Pan-EU sellers; provides VAT-compliant invoices to B2B buyers. Cons: requires the seller to provide cost data accurately; mistakes in the seller's data flow into customer invoices; VCS does not handle every edge case. For most Pan-EU FBA sellers, VCS is the right call once configured correctly.

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