A purchase invoice booked twice is a silent error. Your totals are nearly right, the entry looks normal, and only at the payment run or when the supplier emails do you find out that you processed the same invoice twice — or worse, paid it twice. That kind of searching is exactly what an AI assistant is good at.
Can AI find duplicate invoices in Exact Online?
Yes. Connected to Exact Online, the assistant retrieves your purchase invoices and purchase entries and compares them per supplier on invoice number, amount and date. Anything that appears twice, or almost twice, goes into a list with the reason next to it. Correcting is up to you: the assistant flags, you decide.
How duplicate invoices happen
- The same PDF arrives twice — once by email and once through the scan app, or as a reminder with the original invoice attached.
- Two colleagues process the same invoice.
- A copy with a different number — the supplier sends a corrected invoice, but the old one is never credited.
- A typo in the invoice number — for an exact check, "2024-0153" and "2024-153" are two different invoices.
The last two are why a simple check on exactly the same invoice number is not enough. You also want to see the near-duplicates.
Which data the assistant uses
| What | Tool | What it looks at |
|---|---|---|
| Purchase invoices | purchasing_invoices_search | supplier, invoice date, Your reference (the supplier's number) |
| Purchase entries | financial_purchase_search, financial_purchase_get | entry number, supplier, amount, period |
| Transaction lines | financial_transactions_search | invoice number, G/L account, amount |
Prompts that work
- "Search this year's purchase entries per supplier for invoices with the same amount within 30 days of each other."
- "Which purchase invoices have the same supplier invoice number, even if spaces, dashes or leading zeros differ?"
- "For each suspicious pair, show the supplier, both entry numbers, amounts, dates and whether both have already been paid."
- "Run the same check for supplier Jansen Building Supplies over the past two years."
Always ask for the reason per hit. "Same amount, six days apart, different invoice number" deserves a different judgement than "exactly the same number".
Exact Online without and with an AI connection
| Exact Online without an AI connection | Exact Online with Ledger Botje (MCP) | |
|---|---|---|
| Check on the same invoice number | when booking, per supplier | across the whole financial year, all suppliers at once |
| Near-duplicates (amount + date) | by hand with an Excel export | in one question, with the reason per pair |
| Correcting | in Exact Online | in Exact Online — deliberately |
Where the limit is
Not every pair with the same amount is an error: a fixed monthly rent or a subscription returns every month with exactly the same amount. Have those recurring costs excluded, or name them. And the assistant works with the state of the last synchronisation: an invoice booked in Exact this morning only appears once the cache has been updated.
Correcting — crediting or reversing the duplicate entry — happens in Exact Online. It affects your books and your VAT, and that needs a person.
Prevention is better
Make the check a fixed part of your month-end close, and go through the selected items just before the payment run. How that works is in checking a payment run with AI. Basic is enough for this check: it is all reading. The full tool list is in the tool catalogue.