How an Online Seller Fixed Inventory Costing That Overstated Two Years of Profit
Sam's List Editorial | 2026-08-31
The seller was profitable on paper and broke in the bank. That combination is almost always an inventory problem.
This is an illustrative case study. It is a composite drawn from the eCommerce inventory costing mistakes that recur across accounting engagements, not a report on any single client, and no figures here should be read as a promise of what a similar cleanup would produce for your business.
The Symptom: Great Margins, Empty Account
A consumer products brand selling across Amazon and its own storefront had crossed $4 million in annual revenue. The profit and loss statement showed a gross margin near 52 percent and a healthy bottom line.
The bank account disagreed. Every restock cycle drained it. The owner had taken a line of credit to cover inventory buys and was carrying a balance that never went down.
The trigger for getting help was the tax bill. The return showed income the owner could not find, on a business that felt like it was losing money.
The Root Cause: Two Ordinary eCommerce Inventory Costing Mistakes
The books were not fraudulent or even sloppy in the usual sense. They contained two mistakes that are close to standard among growing sellers.
Purchases were expensed when paid, not when sold. Every inventory payment hit an expense account on the payment date. In months with no restock, margins looked spectacular. In months with a big container payment, they collapsed. Neither month reflected what actually sold, and because purchases and sales were on different rhythms, the annual number was wrong too.
Landed cost was incomplete. Product cost was recorded. Ocean freight, duty, customs brokerage, inbound shipping to the fulfillment centers, and prep fees were all sitting in operating expenses. Those costs belong in the cost of the units they arrived with, which meant the true unit cost was materially higher than the number driving pricing decisions.
Layer those two together and you get a business that thinks it has 52 percent gross margin and actually has something closer to 40, with a balance sheet that has no idea how much inventory it owns.
The Rebuild
The work took a full quarter and ran in four stages.
Establish the opening position. Before anything else, count what exists. Physical inventory on hand, units in transit, units sitting at the fulfillment centers, and units already committed. Without a defensible starting quantity, every layer built on top of it inherits the error.
Build real cost layers. Each purchase order was reconstructed with its full landed cost allocated across the units it delivered, so every SKU carried a cost that included freight and duty rather than just the supplier invoice.
Reconcile the settlement reports. Marketplace settlements are not revenue. They are revenue net of referral fees, fulfillment fees, storage, returns, advertising, and reserves, deposited on a schedule that ignores month ends. Those components were separated so the top line reflected gross sales and the fee categories became visible for the first time.
Move to a monthly close with a real COGS entry. Going forward, purchases hit inventory on the balance sheet and a monthly entry relieved inventory into cost of goods sold based on units actually shipped.
What It Changed
The reported gross margin fell. That was the point, and it was uncomfortable for about a week.
With honest per-SKU costing in place, the owner could see contribution margin by product for the first time. Two products that had felt like solid performers were losing money on every unit once landed cost and fulfillment fees were attributed correctly. Both were discontinued.
Cash stopped being a mystery. The gap between book profit and bank balance had been inventory sitting in a warehouse, and once it appeared on the balance sheet as an asset, restock planning became a decision instead of a reflex.
The tax picture also changed, though not in the direction people expect. Correcting the timing of cost recognition shifts deductions between periods rather than creating them, and inventory rules under section 263A require capitalizing certain costs rather than expensing them immediately. In this composite, the near-term effect was a more accurate return and a better-supported position, not a windfall. Whether a correction produces a refund, an additional liability, or neither depends entirely on the specific facts, and a restatement is real work with real cost.
Where a Specialist Firm Fits on eCommerce Inventory Costing Mistakes
This is the kind of cleanup where industry pattern recognition compresses the timeline. A generalist can absolutely rebuild inventory costing. A firm that reconciles marketplace settlement reports every month already knows which fee categories hide where.
ECOM CPA works with eCommerce sellers in the seven to nine figure range, in business since 2016 with a team of 21 and CPA and Enrolled Agent credentials on staff, serving clients nationwide from a footprint that includes Oregon, New York, California, Delaware, Florida, and Texas. It has a small number of client reviews on its Sam's List profile, so we describe it by specialty and tenure rather than by review count.
The trade-offs are worth stating plainly. Specialist firms cost more than bookkeeping generalists. The firm sets a $1 million revenue minimum, so it is not a fit for early-stage sellers. And no outside firm can rebuild history from records that do not exist, which is why the first question in any cleanup is what documentation survived.
If your profit and loss statement says one thing and your bank account says another, inventory costing is the first place to look. You can compare firms that work with online sellers, with their specialties and verified reviews, in the Sam's List accountant directory.
Frequently Asked Questions
Why does my eCommerce business show profit but no cash? The most common cause is inventory accounting. If purchases are expensed when paid rather than when the units sell, the profit and loss statement swings with your buying schedule instead of your sales, and cash tied up in stock never appears as an asset. Fixing the timing usually explains the gap.
What belongs in landed cost for an online seller? Landed cost generally includes the supplier invoice plus freight, duty, customs and brokerage charges, inbound shipping to fulfillment centers, and prep or labeling fees, allocated across the units in the shipment. Leaving those in operating expenses understates unit cost and overstates gross margin.
Are marketplace deposits the same as revenue? No. A marketplace settlement deposit is gross sales less referral fees, fulfillment and storage charges, returns, advertising, and any reserve held back. Recording the deposit as revenue understates both your top line and your expenses, and hides which fee categories are actually eating your margin.
How long does an inventory accounting cleanup take? It varies widely with the quality of records and the number of SKUs. A focused rebuild covering a couple of years commonly runs a quarter or more of part-time work, and the biggest variable is whether purchase orders, freight invoices, and inventory counts can be reconstructed. Timelines and outcomes differ by business.
About the author: Kimberly Green is the cofounder of Sam's List, where business owners and high earners find vetted CPAs, financial advisors, and fractional CFOs. She's met one-on-one with 400+ financial professionals and writes from the real data behind thousands of client-advisor matches. Ask her anything about finding an accountant - she's heard it all, including the questions people are afraid to ask.