The short answer
A finance or operations manager can use a spreadsheet to make a first pass through a year of supplier payments in an afternoon. Look for repeated payments, unused credits, wrong prices, excess quantities and missed discounts. The result is a list to investigate, not a total you can claim back yet.
Keep each possible error linked to its invoice, payment and supporting record. A matching amount alone proves little. The supplier may have sent two separate orders for the same price. Check the documents before asking for money back.
1. Gather the records
Export a year of supplier payments and paid invoices. Include supplier codes, invoice references, invoice dates, payment dates, amounts and currency. Keep an untouched copy and work in a second sheet. Gather credit notes, agreed price lists, goods received records and payment terms. Keep different currencies apart.
2. Find the same invoice paid twice
Sort payments by supplier, then amount and date. Look for the same amount paid on close dates. Compare invoice references after removing spaces and punctuation in a helper column. Keep the original reference beside it. Check both matches against the invoices and bank records.
The free tool at /tools/duplicate-payment-finder/ does this first check in your browser without uploading the file anywhere. Its matches still need a person to check them.
3. Match payments to credit notes
Export credit notes with their dates, amounts and linked invoice references. A credit note records a reduction in what you owe. Look for invoices paid in full after a credit note was issued. Check whether the credit was already refunded or used against another invoice before adding a finding.
4. Compare prices with the agreement
Export invoice lines with item codes, quantities and unit prices. Match them to the price list that applied on the order date. Look for a charged price above the agreed price. Compare the same pack size and tax treatment. Record only the possible excess, not the whole invoice value.
5. Compare quantities with what arrived
Export invoice quantities and records of goods received, linked by order and item code. Look for more units billed than received. Check later deliveries, returns and pack sizes before treating a difference as an error. Multiply any unexplained extra quantity by its agreed unit price.
6. Check earned settlement discounts
Export payment dates, invoice dates, discount terms and the amounts paid. A settlement discount is a reduction for paying within an agreed time. Look for payments that met those terms but used the full invoice amount. Check which date starts the payment window and whether every condition was met.
The blank findings sheet
Use one row per possible error. Amounts are in pounds. Keep evidence with each finding and update the outcome after the supplier replies.
| Supplier | Invoice refs | What looks wrong | Amount in question | Evidence | Who asks the supplier | Outcome |
|---|---|---|---|---|---|---|
Download this sheet as a file for Excel
A made up worked example
Made up example. All seven rows, suppliers, references and amounts are made up to show the method. Amounts are in pounds. They are possible errors, not money recovered.
| Supplier | Invoice refs | What looks wrong | Amount in question | Evidence | Who asks the supplier | Outcome |
|---|---|---|---|---|---|---|
| Supplier A | A104 and A104 | Same invoice appears in two payments | 1240.00 | One invoice and two payment records | Finance manager | Awaiting supplier reply |
| Supplier B | B-208 and B208 | Invoice number written differently | 360.00 | Matching invoice copies and payment records | Bookkeeper | Check whether both payments cleared |
| Supplier C | C310 and CN310 | Invoice paid after linked credit note | 180.00 | Credit note predates full payment | Finance manager | Check whether credit was used elsewhere |
| Supplier D | D411 | Unit price above agreed price list | 75.00 | Invoice lines and dated price list | Buyer | Ask supplier to check price |
| Supplier E | E512 | Billed quantity above received quantity | 240.00 | Invoice and goods received record | Operations manager | Check later delivery records |
| Supplier F | F613 | Earned settlement discount not taken | 42.00 | Written terms and payment date | Bookkeeper | Ask supplier to confirm discount |
| Supplier G | G714 and G715 | Same amount paid on close dates | 560.00 | Separate invoices and separate delivery records | Finance manager | Closed after checking separate orders |
Download this sheet as a file for Excel
Turn a finding into a clear question
Use the findings sheet to record the amount in question, the evidence and one person responsible for asking the supplier. Send the relevant references and explain the difference. Update the outcome when the supplier replies. Keep possible errors separate from agreed repayments and money actually received.
If you would rather have it done
I can run the whole check for you, paid as a share of what comes back. The share and the work are agreed in writing before I start. The agreement also sets out how to record what comes back. No finding counts as recovered money just because it appears on a sheet.
When this is the wrong fit
This afternoon check is a poor fit when the records cannot be matched to invoices or payment dates. Put those records in order first. It is also the wrong tool for a dispute about the quality of work. A spreadsheet can show a difference, but it cannot decide that dispute.
Where to start
Start with the duplicate check while gathering the other records. Work through the remaining checks as the evidence becomes available. If the year is too large for an afternoon, record what you covered and what remains. Do not describe an unfinished review as a full check.