Should the till sell stock it shows you do not have?
Whether a shop should let its till sell below nil stock, what each choice means for sales and stock counts, and why quantities go wrong in the first place.
By Achekam · · 4 min read · For Retail businesses in South Africa, Nigeria, Kenya
A customer puts a kettle on the counter. The cashier scans it, and the till refuses: according to the system there are none left. The kettle is in the customer's hands. The cashier calls a supervisor, the queue grows, and the customer starts to wonder whether to shop somewhere else.
Every shop with a till faces this sooner or later, and the setting behind it, whether to allow negative stock, is a real decision with costs either way. This article explains what Achekam's till does by default, when refusing the sale costs more than it protects, why quantities drift away from the shelf, and how to set a rule your staff can follow.
What the till does when stock runs out, unless the business allows otherwise
A till sale takes the sold quantity off stock in the same step, at the till's location. If the sale would take the quantity below nothing, the till refuses it, unless the business allows negative stock.
So there are two settings:
- Negative stock not allowed. The till will not sell what the records say you do not have. Quantities can never fall below nothing.
- Negative stock allowed. The till sells, and the quantity at that location goes below nothing. The record is now openly wrong, which is a signal that someone needs to look.
Neither setting changes what is on the shelf. They only change what happens when the record and the shelf disagree.
When refusing a sale costs more than it protects
The case for refusing is control. If the till cannot sell what the books say is gone, nobody can quietly sell stock that was never recorded, and quantities stay meaningful.
The case against is simpler: the goods are in the customer's hand. Refusing a sale you could have made costs you the sale, the customer's patience and sometimes the customer. In a busy shop, a refused sale at the till can end with someone making it work anyway, by ringing up a different product or overriding a price, which damages the records more than a negative quantity would.
A practical way to think about it:
| Your shop | Leaning |
|---|---|
| Quantities are counted often and deliveries reach the records the same day | Do not allow negative stock |
| High-value items where every unit must be accounted for | Do not allow, and investigate every refusal |
| Fast-moving, low-value goods and a busy counter | Allow, with a daily review of anything below nothing |
| Quantities are known to be unreliable | Fix the quantities first; allowing negative stock only hides the cause |
Why stock can read nothing while goods sit on the shelf
Before you decide, find out why your records and your shelves disagree. In Achekam today, the common causes are:
Deliveries do not add stock. Goods received against a purchase order are recorded, but they do not increase the quantity at the location. A product that was delivered this morning can show none in stock this afternoon. How to deal with that is covered in getting new deliveries onto the till quantities.
Opening quantities were wrong. The Item Master records each product's opening quantity when it is created. A rushed or estimated opening figure stays wrong until a count corrects it.
The stock is at another location. Stock is taken at the location of the till that sold it. If the goods were received into the storeroom or the warehouse, the shop floor's quantity does not include them.
The wrong product was scanned before. A cashier who rang up a similar item under another code has left one product too high and another too low.
Stock taken at the location of the till that sold it
Several tills can run at once, each opened at one of the business's stock locations, and with the Warehousing add-on a business keeps those locations on the server with the quantity on hand at each.
That location detail matters for this decision. A shop with a front counter and a back storeroom, recorded as two locations, can show nothing on the shop floor while the storeroom has plenty. The goods are yours, and they are in the building, but they are not where the till looks. Before allowing negative stock, make sure stock is moved, and recorded, to the location the till sells from.
Counting to bring quantities back in line
Whatever you decide, counting is how quantities are put right. With the Warehousing add-on, a stock count sets a location's quantity to what was counted and records the difference as an adjustment.
If you allow negative stock, count anything that goes below nothing within a day or two. The negative quantity tells you exactly which product to count, and at which location. ACCA's article on inventory control covers the techniques behind good stock control, such as re-order levels, and the practical side of managing stock, both of which depend on quantities you can trust. Full stock takes are covered in running a stock take, and product codes that make scanning reliable in stock codes and barcodes for parts.
A rule for who may switch negative stock on
Treat the setting as a policy, not a convenience:
- The owner decides, not the cashier or the shift supervisor on a busy afternoon.
- Write down why, and the date, so the decision can be reviewed.
- Review daily every product below nothing, while it is allowed.
- Count within days anything that stays negative.
- Revisit monthly. If the list of negative products keeps growing, the cause is upstream, usually receiving, and the setting is hiding it.
For one week, have cashiers note every sale the till refuses for lack of stock, find the reason for each, and fix the most common one before you change the setting.
General guidance only, not advice on your own circumstances. Tax and payroll rules change: check the current position with the authority or your adviser.
