How common are duplicate payments?
Duplicate and erroneous payments are a measurable share of spend: APQC puts them at 0.8% of annual disbursements for top performers and 2% for bottom performers.
The figures come from APQC’s Open Standards Benchmarking accounts payable survey, published openly in CFO.com’s Metric of the Month column. Here is what those rates mean for an example company with $20,000,000 of annual disbursements.
| Performance level | Duplicate or erroneous payments | Annual amount at risk |
|---|---|---|
| Top performers | 0.8% of disbursements | $160,000 |
| Bottom performers | 2% of disbursements | $400,000 |
Estimate your own exposure with the duplicate payment risk calculator.
Why duplicate invoices get paid
Duplicates get paid when the same bill enters the process twice and the second copy does not look exactly like the first.
- Multiple channels. A supplier emails a PDF and mails a paper copy, or sends it to both AP and the buyer.
- Reminders and statements. An overdue notice or statement is keyed as a new invoice.
- Duplicate vendor records. The same supplier exists twice, for example “ABC Supply” and “ABC Supply Inc”, so the same invoice number does not collide.
- Invoice number variations. INV-1001, 1001 and 0001001 are the same invoice to a person but different to an exact-match check.
- Credit memos and rebills. A corrected invoice is paid alongside the original instead of replacing it.
- Multiple entities. The same invoice is paid by two subsidiaries or locations.
- Manual entry plus sync. A bill is keyed in the accounting system and also arrives through an integration or bank feed.
The checks that catch duplicates before payment
Use several checks, from exact matches to near matches, because each catches a different kind of duplicate.
| Check | What it compares | Catches |
|---|---|---|
| Exact match | Same vendor and same invoice number | The same invoice entered twice |
| Normalized invoice number | Invoice number with prefixes, punctuation and leading zeros removed | INV-1001 vs 1001; typos in formatting |
| Amount and date window | Same vendor, same amount, invoice dates within a few days | Resubmissions with a new or missing reference |
| Cross-vendor match | Same amount and invoice number across similar vendor records | One supplier set up as two vendors |
| PO balance | Billed to date against the purchase order total | A second invoice that would overbill the PO |
- 1
Step 1
Before entry, check every invoice against open and paid invoices for the same vendor and invoice number. - 2
Step 2
Normalize invoice numbers (strip prefixes, spaces, punctuation and leading zeros) and compare again. - 3
Step 3
Flag invoices from the same vendor for the same amount within a short date window, even with different invoice numbers. - 4
Step 4
Check the same amount and invoice number across vendor records that may be duplicates of one supplier. - 5
Step 5
Compare billed totals with the purchase order so a resubmitted invoice cannot push a PO over 100%. - 6
Step 6
Review flagged items before the payment run, and record why each was released or rejected.
Matching invoices to purchase orders adds a strong backstop: once a PO is fully billed, another invoice against it stands out. See three-way matching.
Controls that prevent duplicates
Prevention is mostly process: one clean vendor record per supplier, one way for invoices to come in, a review before every payment run, and separate people for entry and release.
- Vendor master hygiene. Check tax ID, address and bank details before creating a vendor, and merge or deactivate duplicate records.
- Single intake channel. Ask suppliers to send invoices to one AP inbox or portal, not to individual buyers.
- Payment-run review. Review flagged near matches and unusual amounts before releasing each payment batch.
- Segregation of duties. The person who enters an invoice should not be the one who approves it or releases payment. See invoice approval routing.
- Mark documents as processed. Stamp or tag source documents once entered so copies are easy to spot.
How to find duplicate payments you have already made
Run the same checks over paid invoices for the last one to two years, confirm each hit against the documents, then ask suppliers for refunds or credits.
- 1
Export paid invoices
Pull vendor, invoice number, invoice date, amount, payment date and payment reference for 12 to 24 months. - 2
Run the checks
Look for exact matches, normalized invoice-number matches and same-vendor, same-amount payments close together. - 3
Confirm each hit
Compare the source invoices. Recurring charges such as rent or subscriptions can look like duplicates but are not. - 4
Recover the money
Send the supplier both payment references and ask for a refund or a credit against open invoices. - 5
Fix the cause
Record why each duplicate happened and close the gap, for example by merging vendor records.
How Aequo AP checks for duplicates
Aequo AP compares each new invoice with earlier invoices by vendor, amount, date and invoice number, flags unusual amounts for that vendor, and gives each invoice a duplicate risk level before it is approved.
Flagged invoices go to an exception queue for review, alongside two-way and three-way matching against purchase orders. It syncs with QuickBooks Online, Xero, FreshBooks and Zoho Books.
Frequently asked questions
How common are duplicate invoice payments?
APQC’s Open Standards Benchmarking, published in CFO.com’s Metric of the Month column, found that top performers have 0.8% of annual disbursements going to duplicate or erroneous payments, compared with 2% for bottom performers.
Why do duplicate invoice payments happen?
Usually because the same bill enters the process twice: a supplier emails and mails the same invoice, resends it as a reminder, or bills under a second vendor record, and a slightly different invoice number gets past an exact-match check.
Can accounting software stop duplicate invoices?
Many accounting systems can warn when a vendor and invoice number already exist, but only on an exact match. They miss variations such as INV-1001 and 1001, the same bill under two vendor records, or the same amount with a different reference. Fuzzy matching on amount, date and vendor catches more.
What should I do if I paid an invoice twice?
Confirm both payments cleared, contact the supplier with both payment references, and ask for a refund or a credit against the next invoice. Record the credit in your accounting system so it is applied, and fix the control that let the duplicate through.
How do I find duplicate payments already made?
Export paid invoices for the last 12 to 24 months and look for repeats on vendor plus invoice number, normalized invoice number, and vendor plus amount within a date window. Review each hit against the supporting documents before contacting suppliers.
Who should be able to release a flagged duplicate?
Someone other than the person who entered the invoice. Separating entry, approval and payment release is a basic internal control that makes it harder for a duplicate, accidental or deliberate, to be paid.
Automate matching, approvals and exception handling
Aequo AP captures invoices, matches them to purchase orders and receipts, routes approvals and flags duplicates and exceptions, then syncs with QuickBooks Online, Xero, FreshBooks or Zoho Books.
Related guides and tools
Sources
Checked on October 22, 2026. Vendor capabilities and prices change; confirm current details with each vendor.
- APQC Open Standards Benchmarking, via CFO.com Metric of the Month: Detect and Prevent Duplicate or Erroneous Payments — top performers 0.8%, bottom performers 2% of annual disbursements are duplicate or erroneous payments