Duplicate Invoice Payment Leakage Calculator
Duplicate payments are rarely large per event, but across tens of thousands of invoices they add up. This calculator estimates what your current duplicate-detection rate costs and what a better one would be worth.
Your numbers
Share of received invoices that duplicate an earlier one (re-sent, re-keyed, emailed and mailed).
Share of duplicates stopped before payment.
Recovered through vendor credits or refunds.
Your results
Planning estimate. Measure your real duplicate rate from a payment audit before using it in a business case.
Gross value paid in error vs catch rate
Sweeps Current catch rate before payment from 0 to 100, holding your other inputs fixed.
Duplicate payment scan
Optional: ask for a fuzzy duplicate scan design for your AP history.
Optional. The tool and every export work without this. No spam.
How to use the calculator
Enter yearly invoice volume and average value, an estimate of the share of invoices that duplicate an earlier one, and the share you currently stop before payment. Then enter a target catch rate and the share of leaked money you usually recover. A quick audit of last year's payments, matching on vendor, amount and date, is the best way to find a real duplicate rate.
- Include invoices received by email and paper for the same order.
- Use a value-weighted average if a few large invoices dominate.
- Use a conservative recovery rate.
The formula
Duplicates equal volume times the duplicate rate. Those reaching payment equal duplicates times one minus the catch rate. Gross leakage is that count times average value, and net loss removes the portion later recovered from vendors. Avoided loss is the difference between net loss at the current and the target catch rate. Recovery effort has its own cost, which is not modeled here.
How to read the result
The chart shows leakage falling as catch rate rises. The final points are the expensive ones to reach: exact-match checks on invoice number and vendor catch the easy cases, but fuzzy cases (a changed invoice number, OCR misreads, a re-issued invoice) need fuzzy matching on amount, date and PO. If net loss is small relative to project cost, a simple ERP duplicate check may be enough.
Common mistakes
Assuming the ERP duplicate warning catches everything is the biggest one: it usually matches on supplier plus reference number, so a misread number defeats it. Another is ignoring credit-note offsets, which hide duplicates in net balances. Finally, do not forget that OCR itself can create near-duplicates when the same document is scanned twice.
Frequently Asked Questions
How common are duplicate invoice payments?
Rates differ by company and control maturity. Many audits find a fraction of a percent of invoices, with most caught before payment. Run a sample audit on your own payment history to get a defensible number.
Does the ERP duplicate check not already handle this?
It handles exact matches on fields such as vendor and reference number. A misread or re-keyed number, a statement re-sent as a new invoice or a changed date can slip through.
Can duplicates be recovered?
Often, through refunds or credits from the supplier, but it takes effort and some money is never recovered. Use a conservative recovery rate and treat recovery labor as a cost.
What is a realistic target catch rate?
High nineties is common when exact and fuzzy checks are combined with a review of flagged items, but the right target depends on invoice mix. Use the target as a scenario, not a promise.
If you would like a duplicate scan across your AP history using fuzzy matching on amount, date and PO, Netray can run it on-prem so the data stays inside your network.
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