How to detect duplicate supplier payments

• The same invoice arrives through several channels (email, paper, portal) and is recorded twice.
• The supplier exists twice in the supplier master file, under different codes.
• The invoice number is entered with small differences (zeros, hyphens, spaces).
• The supplier reissues an invoice (a copy) that is processed as new.
• Urgent or manual payments are made outside the normal process.
• Groups with several entities pay the same invoice in different companies.

• Suppliers with repeated names, tax numbers or IBANs in the supplier master file.
• Invoices from the same supplier with the same amount on close dates.
• Debit balances (in your favour) on supplier accounts.
• Credit notes issued by suppliers that were never used.

1. Extract invoices, payments and credit notes covering several financial years.
2. Normalize the data: invoice numbers, tax numbers, supplier names and dates.
3. Look for exact duplicates (same supplier, number and amount).
4. Look for near-duplicates (similar amounts, dates or references).
5. Validate each case against the original invoice and proof of payment.
6. Ask the supplier for a refund or offset, with documentary evidence.

• Block invoices with the same supplier, number and amount in the ERP.
• Keep a clean supplier master file, with tax number and IBAN validation.
• Centralize invoice receipt in a single channel.
• Segregate duties between those who record, approve and pay.
• Reconcile supplier statements regularly.

When invoice volumes are high, there are several systems or entities, or the team does not have time to review several years of data. A profit recovery audit combines data matching tools with experience in recovering amounts from suppliers.