Stopping a supplier invoice being paid twice
How a busy shop stops the same supplier invoice being captured and paid twice when several people handle deliveries, bills and payments.
By Achekam · · 4 min read · For Retail businesses in South Africa, Nigeria, Kenya
Paying a supplier twice is one of the most ordinary mistakes in retail, and one of the hardest to recover from. The supplier rarely notices, or notices and says nothing; the money sits as a credit on their books until someone at your shop thinks to ask. By then the person who captured the invoice may have left, and the second payment looks like any other.
It happens in shops because the paper takes several routes. This article explains how duplicates arise, which controls in Achekam catch them, where those controls stop, and the weekly habit that catches what slips through.
How the same invoice gets captured twice in a busy shop
Picture a clothing store with a manager, a receiving clerk and a part-time bookkeeper:
- The driver hands the receiving clerk an invoice with the delivery. The clerk leaves it in the bookkeeper's tray.
- The supplier also e-mails the same invoice to the shop's accounts address. The bookkeeper uploads that copy.
- At month end the supplier's statement arrives with the invoice on it, and the manager, seeing it unpaid in a hurry, pays it from the statement.
Each person acted sensibly with what they had. Between them, the shop has captured the invoice twice and paid it once from a bill and once from a statement. Variations include a supplier re-sending a "copy" marked overdue, a photo of the invoice sent on WhatsApp, and a supplier registered twice under slightly different names.
One supplier list, checked by name and VAT number
The first control is upstream of the invoice: one supplier list. A business keeps a single supplier list with duplicate checks by name or VAT number, and quotations, orders and bills pick suppliers from it.
If a supplier exists twice, once under its trading name and again under its registered company name, the same invoice can be captured against each without any invoice-level check firing. So clean the list first: merge or switch off duplicates, and make one person responsible for adding new suppliers.
A limit for Nigerian and Kenyan shops: a supplier's VAT number must currently be in the South African format, so Nigerian and Kenyan VAT numbers are refused. Until that changes, the VAT number check cannot help you there; rely on the name check, and keep the supplier's tax number in their details where your team can see it.
The supplier's invoice number on order-matched bills
When you buy through purchase orders, a supplier invoice recorded against an order is matched with what was ordered and what arrived. If price or quantity differ, it is held until someone writes a resolution note.
Posting a matched supplier invoice puts it in the ledger as expense, input VAT and trade payables, and the supplier's invoice number stops it being posted twice. That is the strongest duplicate guard Achekam has, and the reason to put regular stock purchases through purchase orders. A second copy carrying the same supplier invoice number is stopped from posting, however it arrived.
For the full logic of matching an invoice to its order and its delivery, see the three-way match.
Uploaded invoices: possible duplicates wait for a person
Supplier invoices and receipts uploaded to Financial Intake become suggested postings. AI can suggest, but only a person approves and posts. Journals proposed from documents are only candidates, and possible duplicates wait in the Intake Review Queue for a person to decide.
That makes the upload route safer than retyping. Encourage everyone, including the receiving clerk, to upload invoices rather than leave paper in a tray, and make the bookkeeper the only person who approves postings from the queue. When the queue flags a possible duplicate, do not approve it until you have found the original.
Paying from statements and approved bills, not from copies
Bills captured without a purchase order still need care. A business records supplier bills line by line with VAT, and a bill without a purchase order waits for approval before it posts. It can then be paid in full or in parts from a chosen bank account.
The rule that prevents most double payments is simple: pay only from approved bills in Achekam, never directly from a paper invoice, a statement, an e-mail or a WhatsApp photo. If an invoice is not in the system as an approved bill, it is not paid until it is.
Supplier statements are for checking, not for paying. ACCA's article on supplier statement reconciliations explains why a separate record of each credit supplier must be kept and how reconciling the supplier's statement to it finds errors. A duplicate payment shows up there as a credit on the supplier's statement that your records do not explain.
A weekly look at bills awaiting payment
Once a week, before payments are released, the manager or owner spends a few minutes on the list of bills awaiting payment:
- Sort by supplier and look for two bills with the same amount close together.
- Check that every bill has the supplier's own invoice number, not a delivery note number.
- Ask about any bill without a purchase order above the level you would normally order.
- Compare totals for your largest suppliers with their latest statements.
- Note any credits on supplier statements, and ask for them back.
The person who reviews should not be the person who captured the bills. Restaurants face the same pressure with daily food deliveries; see food and beverage supplier bills. Professional firms paying third parties on clients' behalf have their own version, covered in paying counsel and correspondents.
This week, list last quarter's supplier payments from your bank statements, sort them by supplier and amount, and look for pairs. Any you find tell you which of these routes your shop needs to close first.
General guidance only, not advice on your own circumstances. Tax and payroll rules change: check the current position with the authority or your adviser.
