# Duplicate invoice checks in Business Central for wholesalers

Business Central covers part of duplicate invoice checks on its own. Wholesalers receive the same invoice from several places: the supplier's email, a portal, a carrier and a monthly statement.

## Why it matters for wholesalers

- Reissued invoices keep the same lines and total but get a new number, so number-only checks miss them.
- Volume makes a duplicate easy to hide. A $3,000 duplicate among 400 bills a week is not obvious.

## For wholesalers in Business Central

- Tick Ext. Doc. No. Mandatory in Purchases & Payables Setup. Posting is then not possible without the Vendor Invoice No. on an invoice or the Vendor Cr. Memo No. on a credit memo.
- The same rule applies to the External Document No. on general journal lines for vendors with the document type Invoice, Credit Memo or Finance Charge Memo.
- The Your Reference field is another way to hold the supplier's number. It shows on posted documents but is not available on journal lines.
- Search vendor ledger entries by the external document number before you post a bill from a busy supplier.

## What Business Central does on its own

Business Central can make the vendor's invoice number mandatory with Ext. Doc. No. Mandatory and lets you search posted invoices and vendor ledger entries by that number.

- Search for repeats yourself before posting, and check the vendor and amount as well.

Check the vendor and amount as well, because two suppliers can use the same number.

What you need and the setup steps: https://www.pulsify.tech/duplicate-invoice-checks-for-business-central/

## Example

Example Cleaning Supplies sends invoice 88120 by email. The same invoice comes in again from their portal as 88120-R with the same lines and amount.

- Invoice 88120, cleaning supplies: $3,180.00 (Original bill)
- Invoice 88120-R, cleaning supplies: $3,180.00 (Same supplier, same total, same lines and a close number)
- GST on both: $318.00 (Would be claimed twice if both are paid)

The check flags the second bill as a likely duplicate on supplier, amount and lines. It is held, so the wholesaler does not pay $3,498 twice.

## Common mistakes

- Matching on invoice number only.
- Entering a bill from the statement when the original invoice is already in the system.

## Step-by-step guides for Business Central

- How to stop paying a purchase invoice twice in Business Central: https://www.pulsify.tech/how-to/stop-paying-a-bill-twice-in-business-central/

## What Pulsify adds

Pulsify checks every invoice for a duplicate, including bills keyed straight into Business Central, and asks before approval. Pulsify connects to Business Central. We set up the connection for you. More: https://www.pulsify.tech/duplicate-invoice-checker/

## Common questions

### How do I catch the same supplier invoice being entered twice in Business Central?

Ext. Doc. No. Mandatory forces a number to be entered. Search posted entries by that number before you post. Check the vendor and amount as well, since two suppliers can use the same number.

### What should I do if a duplicate was already paid?

Ask the supplier to issue a purchase credit memo or refund. Do not just short-pay the next invoice without telling them. Keep the record so the statement reconciles.

### How do I catch a vendor invoice number that was already used in Business Central?

Turn on Ext. Doc. No. Mandatory so every invoice carries the vendor's number. Before you post, search posted purchase invoices or vendor ledger entries by External Document No. for that vendor.

## Sources

- https://learn.microsoft.com/en-us/dynamics365/business-central/purchasing-ext-doc-no
- https://www.ato.gov.au/businesses-and-organisations/gst-excise-and-indirect-taxes/gst/tax-invoices

Source: https://www.pulsify.tech/duplicate-invoice-checks-in-business-central-for-wholesalers/ (last checked 2026-10-19)