Making GST billing and inventory agree, permanently

Ask two people in a small manufacturing business what the stock of an item is and you will often get two numbers. Neither is wrong on its own terms. One counts what was physically issued; the other counts what was invoiced. The gap between them is every transaction that happened in one system and not yet the other.

One event, both effects

The fix is structural: a dispatch is a single event that moves stock and creates the billing document, in one transaction, or neither happens. The moment those are two separate acts performed by two people at two times, drift is guaranteed and no amount of discipline will close it.

Document the exceptions, do not forbid them

Real businesses ship before paperwork. Material goes out on a challan at 6pm and the invoice is raised the next morning. A system that refuses this simply gets bypassed — the material leaves anyway, and the system now describes a fiction.

So model it: a delivery challan that moves stock immediately and carries a pending-invoice flag, with a list somebody owns. The exception stays visible instead of becoming invisible.

Batches earn their keep

Batch and serial tracking looks like overhead until the first quality complaint, at which point it is the difference between recalling one lot and recalling six months. If your material has a heat number, a lot code or an expiry, capture it at receipt. Retro-fitting it is a stock-take.

Valuation decided once

• Pick a method — weighted average or FIFO — and let no report use another
• Land freight and duty onto cost at receipt, not as a period adjustment
• Post adjustments against a reason code, never as a silent quantity edit
• Reconcile physical count on a rolling schedule, not once a year in a panic

None of this is clever. It is simply decided once, in the system, instead of re-decided monthly by whoever is building the report.