What should I pay attention to when sending invoices and credit notes?

Sending an invoice to a government institution via Peppol

When sending an invoice via Peppol to a government institution, there are a number of important points to keep in mind. In this article, we explain why adding an order number (PO number) is often crucial, and how to fill it in correctly.

Required information for government invoices

Government institutions use Mercurius, the Belgian platform that receives and sorts Peppol invoices for the government. To ensure that your invoice is correctly processed there and reaches the right department, it is often mandatory to include an order number or PO number in the Peppol invoice.

Note: if this number is missing, your invoice will still be delivered, but it cannot be correctly sorted within the government’s administration. This can lead to late or incomplete processing and payment.

What if you don’t fill in the order number?

If you send an invoice without the correct order number:

• the invoice is technically delivered via Peppol;
• but Mercurius cannot automatically assign the invoice to the right department;
• which means payment may be delayed or go wrong;
• and you cannot resend the invoice with a correction (invoices are legally immutable).

In that case, you need to:

1. credit the incorrect invoice;
2. create a new invoice (via duplication);
3. and resend this version with the correct PO number.

How do you add an order number?

1. Open the invoice you want to send.
2. Click on the gear icon at the bottom to open the invoice options.
3. Go to the Peppol tab.
4. In the Advanced Peppol options section, enter the correct Purchase order number (PO).
5. Save and send the invoice via Peppol.

For an overview of all available reference fields (buyer reference, contract and project number), see Advanced Peppol options: references.

Peppol invoice options

Double-check with your customer

We recommend always checking with your customer first whether an order number is required. In 9 out of 10 cases with government agencies, it is, but it remains the sender’s responsibility to coordinate this correctly.