How to Investigate Inventory Variances

What is an inventory variance?

An inventory variance is the difference between the quantity recorded in the inventory system and the quantity physically counted within the same inventory scope. A negative variance means the physical quantity is lower than the system quantity. A positive variance means more stock was counted than the system shows.

Net variance is the total of every item variance added together with its sign, so shortages reduce the total and overages offset it. If one SKU is short 35 units and another is over by 20 units, the net variance is −15 units. Net variance shows the overall balance of the count, but it can hide offsetting errors: a large shortage and a large overage can cancel out and still leave the net variance close to zero. Gross variance (also called absolute variance) adds the size of each variance without regard to sign, so the same two items give a gross variance of 55 units. Use net variance to reconcile the total against the system, and gross variance to judge how much error the count actually found.

A variance should not be treated as an automatic instruction to adjust the system. It is a signal that a transaction, movement, count or control may need investigation. Correcting the number without identifying the cause can allow the same issue to happen again.

Inventory variance investigation checklist

Common causes of stock discrepancies

• Receiving errors: incorrect quantity, wrong SKU, duplicate receipt or unposted receipt.
• Picking errors: wrong item, excess issue, short pick or unconfirmed dispatch.
• Location errors: stock moved physically without a corresponding system transfer.
• Unit-of-measure errors: cartons recorded as pieces, or pack-size conversions applied incorrectly.
• Damage and expiry: unusable stock whose physical location or system status was not updated. Stock in quarantine may still be part of total on-hand stock.
• Count errors: mixed batches, hidden stock, double counting or missed locations.
• Master-data problems: duplicate SKUs, incorrect barcodes or outdated pack configurations.
• Unauthorized movement: stock removed, used or relocated without documentation.

Worked example: investigate a 35-unit shortage

This fictional example uses one SKU, one unit of measure and the same stock scope at the count cutoff.

The warehouse should not immediately reduce the system by 35 units. The investigation should first check recent receipts, dispatches, pending transfers, damage records, staging areas and units of measure. If the shortage remains unexplained after those checks, it should be documented and escalated according to the organization’s approval process.

What if an unposted dispatch explains 20 units?

1. Verify the dispatch. Suppose the investigation confirms that 20 units left before the cutoff, belong to this SKU and scope, and have not already been issued in the system. A pick list alone is not proof that goods left; reconcile the shipment evidence and transaction history.
2. Correct the source transaction. Follow the authorized issue-posting procedure. With no other movements in this example, the corrected system quantity is 1,250 − 20 = 1,230 units.
3. Recalculate the remaining difference. Physical stock of 1,215 against corrected system stock of 1,230 leaves −15 units, worth −USD 120 at USD 8 each.
4. Keep the remainder unresolved. Continue checking locations, transfers, receiving and stock status. Escalate the remaining difference with evidence if no cause is confirmed.

Do not post both the 20-unit issue and the original 35-unit shortage adjustment. That would correct the same 20 units twice. If subsequent movements occur, reconcile those movements before comparing the current system balance with the earlier count.

What should an investigation record include?

• Case details: reference, SKU, UOM, warehouse/bin, batch or serial, stock status and count date/time.
• Count evidence: original count, independent recount, counters and the system balance at the cutoff. Use a stock count sheet.
• Transaction evidence: receipt, issue, transfer and return references, quantities, timestamps and posting status.
• Findings: what each check established, conflicting evidence and any remaining unknowns. A stock difference alone does not prove theft or supplier error.
• Decision and follow-up: proposed correction, reviewer/approver, action owner, due date, posting reference and final reconciliation.

Use the Inventory Variance Report Generator to calculate and record differences. A calculated report supports the investigation; it does not establish the cause or approve a correction.

When should inventory be adjusted?

An adjustment should be made only after the recount and transaction review are complete, the variance is documented, and the required approval has been obtained. The supporting record should show who counted the stock, who investigated it, the reason code used and who approved the correction.

• Wrong location: verify both bins and use the appropriate transfer. A bin shortage and matching excess elsewhere may leave warehouse-level stock unchanged.
• Missing or incorrect transaction: correct the receipt, issue, return or transfer through the authorized process where possible.
• Wrong UOM: confirm the actual pack conversion and correct the affected records. Do not compare cartons directly with individual units.
• Damaged or held stock: distinguish physical quantity from saleable status. A status change or approved write-off may be needed; do not automatically treat held stock as missing.
• Confirmed residual difference: document the remaining variance and follow the required approval process for a quantity adjustment.

For damaged or expired stock, use the Damage / Write-off Form to record the affected quantities, evidence and required authorization. Confirm whether the correct action is a status change, supplier return or approved write-off before posting.

High-value, repeated or unusual variances should receive additional review. A pattern affecting the same SKU, shift, customer, supplier or location may indicate a process weakness rather than an isolated counting mistake.

Before closing the case, verify the posted transaction, reconcile the corrected balance and record who will check whether the corrective action prevents recurrence. Use thresholds and approval roles from your own procedure; this guide does not set a universal value limit.

Use the Inventory Adjustment Form to document a proposed correction and its approval. Attach the count and investigation evidence; completing a form does not authorize posting an adjustment.

If you want AI help organizing your notes, Kriyano’s Inventory Discrepancy Investigation Prompt can help draft a checklist of further checks. Use anonymized details and verify suggestions against your records; a generated explanation is not evidence of the cause.

How to reduce future variances

• Use barcode scanning where practical and validate pack sizes in the item master.
• Complete system transactions at the time of the physical movement.
• Keep receiving, storage, quarantine and dispatch areas clearly separated.
• Perform regular cycle counts based on item value, movement and risk.
• Investigate recurring reason codes and assign corrective actions.
• Train staff on location control, batch handling and units of measure.
• Track variance quantity, variance value, count accuracy and repeat discrepancies.

Frequently asked questions