Inventory accounting isn’t just about tracking what sits in your warehouse. It drives your margins, cash flow, taxes, and valuation. Yet, most businesses mess it up-often in dozens of small but costly ways. Below are 74 of the most common mistakes we see.
Setup Errors
- Using the wrong costing method (FIFO vs. LIFO vs. weighted average).
- Not aligning accounting method with IRS elections.
- Failing to set SKU-level tracking.
- Treating all inventory as one bucket.
- Ignoring landed costs.
- Not reconciling beginning inventory to prior-year ending inventory.
- Not mapping chart of accounts properly.
- Using cash basis when accrual is required.
- Mixing COGS with operating expenses.
- Ignoring consignment inventory.
Purchasing Mistakes
- Not capturing vendor deposits as assets.
- Recording purchases as expenses.
- Double-counting freight.
- Excluding tariffs or duties.
- Not capitalizing packaging.
- Misclassifying returned goods from suppliers.
- Skipping purchase accruals at period end.
- Failing to reconcile purchase orders to invoices.
Inventory Tracking Issues
- No cycle counts.
- Relying solely on system quantities.
- Ignoring shrinkage.
- Not writing off obsolete stock.
- Overstating slow-moving SKUs.
- Skipping negative inventory adjustments.
- Not tracking lot numbers or expiration dates.
- Treating samples as inventory.
- Ignoring promotional giveaways.
- Not segregating damaged goods.
Production & Assembly Errors
- Not tracking raw materials separately.
- Failing to use bill of materials.
- Overstating WIP (work in progress).
- Understating finished goods.
- Not absorbing labor into COGS when required.
- Overhead allocation errors.
- Ignoring scrap.
- Recording production twice.
- Failing to reconcile production runs.
Sales & COGS Errors
- Recognizing revenue without relieving inventory.
- Delayed COGS recognition.
- Misclassifying shipping as COGS.
- Not matching returns with inventory add-backs.
- Forgetting to restock canceled orders.
- Using estimates for COGS instead of actuals.
- Recording COGS to the wrong period.
- Ignoring Amazon or 3PL inventory timing.
- Skipping adjustments for lost-in-transit goods.
Valuation Errors
- Not applying lower of cost or market/net realizable value.
- Overstating inventory to boost profits.
- Failing to impair obsolete SKUs.
- Treating promotional bundles incorrectly.
- Not allocating landed costs consistently.
- Ignoring foreign currency fluctuations.
- Overvaluing consigned inventory.
- Counting safety stock twice.
Technology Gaps
- Relying on spreadsheets.
- Not integrating POS with accounting.
- Misconfigured ERP rules.
- No audit trail on adjustments.
- Not reconciling 3PL reports.
- Double integration feeds (Shopify, Amazon, ERP).
- Ignoring time lags between systems.
Period-End Problems
- Not performing physical counts.
- Recording adjustments without approval.
- Carrying “suspense” balances month-to-month.
- Closing books without reconciling inventory to GL.
- Failing to accrue freight-in.
- Misstating cut-off for shipments in transit.
- Not tying subledger to control account.
- Reversing accruals incorrectly.
- Leaving unadjusted variances open.
Strategic Oversights
- No documented inventory policy.
- Not training staff on accounting impacts.
- Treating inventory as afterthought vs. working capital.
- Ignoring the tax planning impact of inventory methods.
Bottom line: Inventory accounting errors compound. Fixing them requires clean setup, tight controls, reconciliations, and consistent policies. If your numbers seem off, they probably are.