Duplicate invoice detection

Overview

The project in brief

What we are doing

Pause a likely duplicate invoice before it posts, so a person can confirm it before anyone pays it twice. Each invoice is compared with past ones on supplier, invoice number, amount and date. Exact matches are blocked. Near matches are paused with the earlier invoice beside the new one.

Why it matters

A paid duplicate means supplier chasing and credit notes. The same invoice can arrive by email and by post, or come back with a small change to the number or amount. Your system may already block an exact repeat, but a slightly different copy can get through and surface later, by supplier call or audit.

Who it is for

Fits an AP team whose invoices are already captured in an ERP or AP system that can pause an invoice before posting.
Controller: usually the champion, and responsible for the controls and the review queue.
Sponsor: usually the CFO or a finance leader, who signs off the pilot results. The sponsor can be someone else, and the controller can sponsor too.
AP manager: owns the matching rules and the review queue day to day.
Reviewer: decides each paused invoice and records a reason.
A second person: checks released invoices each month.
System admin: confirms the system can pause an invoice.

What changes

Before: an exact repeat is blocked. A changed copy can slip through and be found later.
After: near matches are paused with the earlier invoice beside the new one. A person releases it or confirms a duplicate, with a reason.
Cost: a paused invoice adds a review step, so the pilot counts false alarms first.

This is an illustrative improvement approach, not a final solution design. The workflow, level of automation, integrations, and review requirements will depend on your existing tools, available capabilities, data quality, company policies, and team needs. Confirm these during discovery and a controlled pilot before implementation.

Next: what it could move

Impact

What it could move

Target. A person reviews and decides a paused invoice in under 10 minutes of hands-on time, against your own measured baseline. This figure is a starting assumption for you to confirm.

Steps: Paused invoices add a review step. Unwinding paid duplicates may take fewer steps.; Depends on workflow design
Cycle time: Paused invoices wait for a person. Clean invoices pass straight through.; Depends on workflow design
Exception loops: Fewer paid duplicates may mean fewer refund requests and credit note chases.; Possible downstream benefit
First-time-right rate: More invoices may be right first time, with duplicates caught before posting.; Potential direct benefit
Cost per invoice: Stopping duplicates may avoid recovery work. Time on false alarms counts against it.; Possible downstream benefit

These are expected effects, not measured results. Time 10 to 20 paused invoices to set your own baseline.

Show detail

How to check it in a pilot

Steps: Count steps and minutes on paused invoices, then compare with unwinding today.
Cycle time: Time from pause to decision, apart from the rest of the cycle. This is waiting time, not the review minutes above.
Exception loops: Count duplicates found after payment and the work each causes.
First-time-right rate: Track first-pass match rate and the share of paused invoices that are false alarms.
Cost per invoice: Compare review minutes with the value and effort of duplicates stopped.

How the sum works

Invoices paused per year times (current minutes minus target minutes) equals minutes saved per year

Next: what you need and how to start

Plan

From first checks to go live

What you need first

Data: Invoice number, supplier, amount and date captured consistently.
Supplier master checked for duplicate supplier records.
Access: An ERP or AP system that can pause an invoice before posting.
Past invoices to test on.
Known duplicates from the last year, late finds included.
People: Someone who owns the review queue and has time to work it.
A reviewer.
A system admin.

Start on past invoices

1
Confirm the basics
- Check your system can pause an invoice.
- List every route invoices take in.
- Name the rules owner.
2
Build a test set
- Collect known duplicates from the last year.
- Mix in ordinary invoices, including changed numbers and amounts.
- Set how close a match must be to pause.
About 100 invoices is a starting assumption to confirm.
3
Replay past invoices
- Nothing live is paused or released.
- A person reviews each paused invoice.
- Time each review and count false alarms and misses.
- Tune the rules, then rerun.
4
Go live
- Switch on blocking and pausing.
- Set reason codes and name the monthly reviewer.
- Write the handover SOP.

Nothing goes live until step 4. Effort: the pilot is mostly AP time with some configuration help. Production depends on your system and supplier data.

Tools we work with

You do not need a partnership with a tool for us to work with it.

ERP and accounting
Keeps the invoice records each new invoice is compared with.
- Your ERP or AP system
- QuickBooks
- NetSuite
- Xero
Documents and storage
Where invoice files, your test set and the decision log can be kept.
- Box
- Dropbox
- Google Drive
Work and AI (optional)
An AI model, such as Claude, can help read and compare invoices if you want fuzzy matching beyond rules.
- Claude

Where the data moves

Invoices arrive
Your ERP keeps the records
Near matches are paused for a person to decide

Next: what to check before you trust it

Trust and control

Checks, risks and who decides

What to check before you trust it

How many known duplicates the rules block or pause, and which kinds slip through.
How many good invoices get paused, and the review minutes spent on them.
How many paused invoices are released versus confirmed as duplicates, and how long each waits.
Duplicates found after posting or payment during the pilot.
Keep a log of every paused invoice (decision, reason, who) and your rule change log.

Known risks

False alarms pause good invoices, and people start releasing without checking.
A changed number or amount is not close enough to match.
One supplier under two records hides the earlier invoice.
Invoices that enter outside the normal route skip the check.
Rules go stale as invoice formats change.

What stays with a person

Setting and tuning the matching rules.
Deciding every paused invoice: release it or confirm a duplicate, with a reason.
A monthly review of released invoices by someone other than the processor.
Approval, payment, supplier record cleanup and recovering money already paid stay outside this project.

The system never approves an invoice or pays one.

Your final solution will depend on your tools, data, processes, and review requirements.