An ecommerce profit and loss statement lies in four predictable places, and once you know where to look you can audit one in about ten minutes. The four are: a revenue line that is actually net deposits, a cost of goods sold figure that is a quarterly estimate wearing a monthly disguise, marketplace fees buried inside revenue instead of sitting in operating expenses, and an inventory number that has not been touched since the last physical count. Every one of those distortions moves your reported margin in a direction that flatters you.
Read the statement in the order below, work through the example, and you will know whether your reported margin means anything.
Line one: is revenue gross or net?
Start at the top and ask a single question. Does the revenue figure equal what customers paid, or what the marketplace deposited?
These are different by 15 to 30 percent for most sellers. Amazon’s published referral fee schedule charges 15 percent in Home and Kitchen, Toys and Games, Sports and Outdoors, Office Products and Tools and Home Improvement; 8 percent in Consumer Electronics and Computers; 12 percent in Automotive and Powersports; and a tiered structure in Clothing and Accessories of 5 percent at or under $15.00, 10 percent above $15.00 through $20.00, and 17 percent above $20.00. Media items carry 15 percent plus a $1.80 per item closing fee. Add fulfilment, advertising, storage and returns processing and the spread between customer payment and seller deposit gets wide.
The test: divide reported revenue by reported units sold. If the result is meaningfully below your average selling price, your revenue line is net of fees. That is not merely a presentation preference. It makes your gross margin percentage meaningless, because the denominator is wrong, and it makes marketplace fees invisible as a cost you could manage.
Fix: revenue records what the customer paid. Every marketplace deduction becomes its own expense line.
Line two: is cost of goods sold a calculation or a guess?
This is the most common failure and the most consequential. Ask your bookkeeper how the COGS figure on last month’s statement was produced. There are three possible answers and only one of them is good.
“It is purchases during the month.” This is not cost of goods sold, it is cash spent on inventory. In a month you place a large purchase order, margin collapses. In a month you place none, margin looks spectacular. The statement is tracking your buying calendar, not your business.
“It is a percentage of revenue we apply.” Better, and still a plug. It tells you what you assumed, not what happened, and it will never surface the SKU whose landed cost rose 14 percent when your freight forwarder repriced.
“It is units sold multiplied by the actual landed cost of those specific units.” Correct. This is what the accrual method requires and what the IRS explains in Publication 538 on accounting methods and inventory. It also requires a system that knows the landed cost of each unit at the moment it ships, which is a real operational requirement rather than a spreadsheet habit.
Line three: where did the marketplace fees go?
Marketplace fees belong in operating expenses on their own lines, ideally split by type: referral or commission, fulfilment, storage, advertising, returns processing, and settlement adjustments. Sellers who net them against revenue lose the ability to see which fee category is growing.
This matters more than it used to. Marketplace fee schedules change on published timetables and the changes are not small. Amazon documents its US fulfilment fee changes on its own Seller Central pages with effective dates, and the sensible practice is to date every fee assumption in your model and re-check it when the card changes rather than carrying last year’s number forward.
Test: if your profit and loss statement has a single line called “Amazon fees,” you cannot answer the question “did our fee burden rise because of volume, mix, or a rate change?” Split it.
Line four: does the inventory balance move every month?
Open the balance sheet next to the profit and loss statement. If inventory is a round number that changes only after a physical count, cost of goods sold on the income statement is an estimate by definition, because the two figures are mathematically linked. Beginning inventory plus purchases minus ending inventory equals COGS. Freeze one and you have fabricated the other.
The worked example
Two versions of the same month for the same seller. First, the version most sellers see:
| Revenue | $186,400 |
| Cost of goods sold | $74,600 |
| Gross profit | $111,800 |
| Gross margin | 60.0% |
Sixty percent gross margin on physical products would be a very good business. Now the same month, restated correctly:
| Gross sales (what customers paid) | $241,300 |
| Returns and refunds | ($11,800) |
| Net sales | $229,500 |
| Cost of goods sold (units shipped x landed cost) | ($91,200) |
| Referral and commission fees | ($33,100) |
| Fulfilment fees | ($26,400) |
| Storage fees | ($4,300) |
| Advertising | ($21,700) |
| Contribution margin | $52,800 |
| Contribution margin percentage | 23.0% |
Same business, same month, same bank balance. The first statement reported 60 percent. The second reports 23 percent. The difference is not accounting philosophy. The first version netted $54,900 of marketplace fees against revenue, understated COGS by $16,600 because it used a percentage assumption rather than actual landed cost, and buried advertising somewhere below the gross profit line where nobody looks.
The operator running on the first statement will happily approve a 10 percent discount promotion, because on 60 percent margin that is comfortable. On 23 percent contribution margin, a 10 percent discount removes more than 40 percent of the contribution on every unit sold.
The audit sequence
- Divide revenue by units. Compare to average selling price. Establishes gross versus net.
- Ask how COGS was calculated. Accept only “units sold times actual landed cost.”
- Count the fee lines. One line is a red flag. Four or more is a working system.
- Check whether the inventory balance on the balance sheet moved this month.
- Confirm advertising sits above the contribution line, not buried in general overhead.
- Recalculate gross margin yourself from the restated figures and compare to the reported number.
If steps one through four all come back clean, your statement is trustworthy and you can make pricing decisions from it. If any of them fail, the margin number on the page is a number, not a measurement.
What it takes to fix it
The manual version is a monthly landed cost calculation per SKU, a chart of accounts with separate fee categories, and a perpetual inventory count that updates as units ship. At a few hundred orders a month a disciplined bookkeeper can hold that together in a spreadsheet. Past a few thousand orders across multiple marketplaces, the reconciliation volume outruns manual effort and sellers move to software that posts settlement detail and cost of goods sold automatically. Platforms in that category include A2X and Link My Books for settlement journals, and ConnectBooks, which handles SKU-level profit and loss and automated cost of goods sold across Amazon, Shopify, Walmart, TikTok Shop and eBay into QuickBooks or Xero.
Whichever route you take, the diagnostic stays the same. A profit and loss statement is a claim about your business. The four lines above are where the claim usually breaks, and ten minutes with a calculator will tell you whether yours holds.