Most e-commerce sellers know their product cost and selling price. Far fewer know their true profit after every fee, charge, and deduction has been accounted for. The gap between perceived margin and actual margin is where e-commerce profitability is most often misread.
What happens between the sale price and your bank deposit
A product with a £25 selling price and a £8 manufacturing cost looks like a healthy £17 gross margin. But by the time marketplace fees are applied, the reality is very different:
| Cost Component | Amount |
|---|---|
| Selling price | £25.00 |
| Product cost (COGS) | (£8.00) |
| Amazon referral fee (15%) | (£3.75) |
| FBA fulfilment fee | (£3.20) |
| FBA storage (monthly average per unit) | (£0.40) |
| PPC advertising (average per unit sold) | (£2.50) |
| Returns & refunds (estimated 5%) | (£1.25) |
| True profit per unit | £5.90 |
| True margin | 23.6% |
The perceived 68% gross margin is 23.6% after platform costs. And this does not yet include shipping to the fulfilment centre, customs duties on imported goods, or your business overheads. Many sellers discover that their best-selling products are their least profitable.
Why net payouts are misleading
Amazon and Shopify deposit a single net payout to your bank account. This figure has already had all fees, refunds, and charges stripped out. If you record this deposit as "sales" in your accounts, every financial metric you calculate from it is wrong, your gross revenue, your expense ratios, your VAT position, and your profit margin.
This is why proper digital bookkeeping with marketplace integration software is essential. Our E-commerce VAT & Marketplace Accounting guide covers the full payout reconciliation process.
How to track true profitability
1. Unpack every payout with A2X or Link My Books
These tools connect to your marketplace API and break each net payout into its component transactions, gross sales, referral fees, FBA fees, advertising, refunds, and post them individually to Xero.
2. Calculate landed costs per product line
Include manufacturing, freight, customs duty, and import VAT. Without accurate landed costs, your COGS is understated and your margins look better than reality.
3. Track advertising spend as a cost of sale
Amazon PPC and Shopify ad spend should be allocated against the products they promote, not buried in general marketing expenses. This reveals your true ROAS (Return on Ad Spend) per SKU.
4. Review management accounts by channel
Management accounts that split revenue and costs by marketplace channel (Amazon UK, Amazon DE, Shopify, etc.) reveal which channels are genuinely profitable and which are subsidised by others.
The tax angle
Marketplace fees are legitimate business expenses and reduce your Corporation Tax liability (or your Income Tax if you are a sole trader). But they can only reduce your tax bill if they are properly recorded. Recording net payouts as sales means these expenses are invisible to your accounts, and invisible to HMRC. You end up overpaying tax because your reported profit is higher than your actual profit.
Frequently asked questions
How much does Amazon charge sellers?
Amazon's total cost varies by category but typically runs 30-45% of the selling price when you combine the referral fee (8-15%), FBA fulfilment fee (£2-5 per unit), storage fees, and advertising. Most sellers underestimate total costs by 10-15%.
Should I use FBA or fulfil orders myself?
FBA is usually more cost-effective for high-volume, small-to-medium sized products. Self-fulfilment can be cheaper for bulky, low-volume, or high-margin items. The only way to know is to calculate the landed cost per unit under both models, which is exactly what our management accounts are designed to show.
When should I switch from sole trader to limited company?
For most e-commerce businesses, the tipping point is consistent annual profit above £30,000-40,000. At that level, the Corporation Tax and salary/dividend structure saves more than the additional compliance costs. Use our Incorporation Decision Tool to run the numbers.