Xero duplicate bills: what Xero's check catches, and what it misses

How Xero's duplicate bill check works

When a bill is approved, Xero compares three fields with your existing bills and credit notes: the supplier contact, the reference, and the amount. If all three match, it shows a duplicate warning above the bills list and lets you review the pair. It is a warning, not a block, and it depends on all three fields matching exactly.

Duplicates that get past it

• A one-character difference in the reference, such as INV-2026-0412 keyed as INV-2026-0413.
• A small amount difference, for example when a reminder copy adds a rounding cent or a fee.
• The same supplier under two contacts, so the bills are never compared.
• A changed bank account on an otherwise normal-looking bill. That is a fraud signal, not a duplicate, and a duplicate check does not look at it.

How to check your Xero bills for near-duplicates

1. Export your bills from Xero to CSV or XLSX, with supplier, reference, amount, and date columns.
2. Upload the file to a free AP Risk Scan and confirm the column mapping. If your export includes the supplier's bank account, map that column too.
3. Review the flagged pairs. Each one shows the matching bill and which fields matched: invoice numbers at least 90% similar, amounts within 1%, and issue dates within 14 days.

To keep checking new bills each month, subscribe to Invoice Firewall and upload each month's export. See how the matching works in how to detect duplicate invoices.