# Duplicate invoice checks for Business Central

Business Central covers part of duplicate invoice checks on its own. Pulsify checks every invoice for a duplicate, including bills keyed straight into Business Central, and asks before approval.

A duplicate invoice check stops the same supplier bill being entered and paid twice.

## 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.

## What you need in Business Central

- Purchases & Payables Setup access

## Setting it up in Business Central

Where to find it: Purchases & Payables Setup > Ext. Doc. No. Mandatory

1. Open Purchases & Payables Setup and turn on Ext. Doc. No. Mandatory.
2. Enter the vendor's invoice number in Vendor Invoice No. on every invoice.
3. Search posted purchase invoices by that number before posting a new one.
4. Search vendor ledger entries by External Document No. to find repeats.
5. Use Your Reference only for extra notes.

## Good to know in Business Central

- Check the vendor and amount as well, because two suppliers can use the same number.
- Vendor ledger entries keep the number after posting.

## How to do it in Business Central

### How to stop paying a purchase invoice twice in Business Central

Before you enter a purchase invoice in Business Central, search the vendor's bills for the same number or amount. Use one reference format and check the payment journal and Suggest Vendor Payments for repeats. Full guide: https://www.pulsify.tech/how-to/stop-paying-a-bill-twice-in-business-central/

## What Pulsify adds

1. Pulsify checks every invoice against earlier ones on invoice number plus supplier, tax ID or date.
2. Bills keyed straight into Business Central count too.
3. A file identical to one already uploaded is held. A person can process it anyway.
4. A suspected duplicate asks the approver to confirm with Approve anyway.

Pulsify connects to Business Central. We set up the connection for you.

What Pulsify does not do:

- Pulsify never matches duplicates on amount alone.
- A duplicate flag is a warning. The approver decides.

## Common questions

### 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.

### Where do I search for a number already used?

Search posted purchase invoices or open vendor ledger entries and filter on the External Document No. Do it before you post a new invoice from the same vendor.

### Why do duplicates happen?

The same invoice arrives by email and post, a supplier resends it as a reminder, or two people enter it. A statement can also be keyed as a bill.

## Sources

- https://learn.microsoft.com/en-us/dynamics365/business-central/purchasing-ext-doc-no

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