You run a stock report from your billing software. It says you have 47 units of a product. You walk to the shelf and count 42. Five units are missing. This gap — between "book stock" (what your system says) and "physical stock" (what you can actually touch and count) — is one of the most common and most frustrating problems in retail and distribution.
The mismatch is rarely theft, though theft does happen. More often, it is a combination of small operational errors that compound over time. Understanding the causes is the first step to reducing them.
Common causes of inventory mismatch
1. Billing errors at the counter
The operator bills item A but hands the customer item B. The system deducts from A's stock; the shelf loses a unit of B. Now both items have wrong counts, in opposite directions.
This is especially common in stores with similar-looking products, loose items sold by weight, or when item names and codes are confusing.
2. Purchase entry mistakes
A supplier delivers 50 units. The purchase entry is recorded as 55. The book stock is immediately overstated by 5 units. The reverse also happens — under-recording purchases means your system shows fewer units than you actually have.
3. Returns not recorded
A customer returns a product. The shop owner takes it back and puts it on the shelf, but nobody records the sales return in the system. The system still shows it as sold. Physical stock goes up; book stock stays the same.
4. Damage, expiry, and shrinkage
Products get damaged in storage, expire on the shelf, or spoil before they are sold. If these are removed from the shelf but not recorded as stock adjustments in the system, the book stock stays inflated.
5. Unit of measurement confusion
You purchase a product in boxes of 12 and sell it individually. If the system is not configured to handle this conversion correctly, purchasing one box might add 1 to stock instead of 12, or selling one unit might deduct a full box.
6. Pilferage and theft
The least common cause in most businesses but the most emotionally charged one. Before concluding that stock is being stolen, eliminate the five causes above. In practice, process errors account for 80–90% of mismatches in well-run small businesses.
How to do a stock audit
A stock audit is simply the process of counting your physical stock and comparing it to your book stock. It sounds simple but requires discipline.
Full stock count
Shut the shop (or at least stop billing) and count everything. This is practical for stores with under 2,000–3,000 SKUs. Do it quarterly at minimum, monthly if you have high-value inventory.
Process:
- Print a stock report from your system as of the count date and time
- Count every item on the shelf, in storage, and in transit (if applicable)
- Record the physical count on the same report
- Calculate the difference for each item
- Investigate items with significant discrepancies
- Make stock adjustments in the system with proper documentation
Cycle counting
For larger inventories, count a portion of your stock each day or week, rotating through all items over a set period. Prioritise high-value and fast-moving items for more frequent counts.
A practical rotation: Divide your inventory into three groups:
- A items (top 20% by value): count monthly
- B items (next 30% by value): count quarterly
- C items (remaining 50%): count every six months
Random spot checks
Pick 10–20 items at random each week and verify the count. This catches systemic errors (like a unit-of-measurement problem) faster than waiting for a full count.
Classifying mismatches
Not all mismatches are equal. After counting, classify each discrepancy:
| Category | Example | Action | |---|---|---| | Data entry error | Purchase recorded with wrong quantity | Correct the entry, trace the original document | | Unreported damage/expiry | Expired medicines removed from shelf but not written off | Record stock adjustment, tighten expiry tracking | | Unit conversion error | System shows stock in boxes, shelf has individual units | Fix the item master, recalculate stock | | Process gap | Returns accepted but not entered | Create a return entry workflow, train staff | | Unexplained shortage | No identifiable cause | Flag for investigation, adjust if not resolved in 30 days |
Document every adjustment. Your accounting system should maintain an audit trail showing who made the adjustment, when, the reason, and the before/after quantities.
Reducing mismatches going forward
Fix the item master first
Most inventory problems start with a poorly maintained item master. Ensure every item has:
- A unique code (barcode if possible)
- Correct unit of measurement for purchase and sale
- Defined conversion factors (e.g., 1 box = 12 units)
- Correct opening stock balances
Use barcode scanning
Barcode scanning at the billing counter eliminates the "billed item A, gave item B" problem almost entirely. A basic USB barcode scanner costs ₹1,500–₹3,000. The return on investment — in reduced billing errors alone — is typically under two weeks.
Record every stock movement
Every item that enters or leaves your inventory should create a transaction in your system:
- Purchases: goods received note
- Sales: invoice
- Returns (inward): sales return / credit note
- Returns (outward): purchase return / debit note
- Damage/expiry: stock adjustment
- Internal transfers: transfer note (if you have multiple locations)
- Free samples/promotional giveaways: stock adjustment
If any of these movements happen without a system entry, your book stock drifts.
Make adjustments properly
When you find a mismatch and need to adjust stock, use a dedicated stock adjustment feature — not by editing old purchase or sales entries. A stock adjustment should:
- Record the item, quantity adjusted (positive or negative), and the date
- Require a reason category (damage, expiry, count correction, theft, etc.)
- Post the value to the appropriate expense or income account in your books
- Be visible in an audit trail report
Review the adjustment report regularly
Run a monthly report of all stock adjustments. If you see the same items appearing repeatedly, that item has a systemic issue — wrong UOM, frequently damaged in transit, or being pilfered. Address the pattern, not just the individual count.
The accounting side
Inventory mismatches are not just an operations problem — they affect your books:
- Stock written off due to damage or expiry is a business expense, deductible for income tax
- Unexplained shortages must be recorded, but large, unexplained write-offs can attract scrutiny during tax assessments
- Overstated book stock means overstated assets on your balance sheet and understated cost of goods sold — which means you are reporting higher profit than reality and paying more tax than you should
- At GST time, if your stock register shows goods that don't physically exist, it raises questions about unrecorded sales — and unrecorded sales mean unreported GST liability
Keep your stock clean. It protects your books, your tax position, and your sanity.