When you send a sales invoice over Peppol, it can come back as undelivered. Billtobox records the exact reason on the invoice itself, so you can almost always fix it yourself and resend. This article shows you where to find the reason and what each error means.
Step 1: find the exact reason
The delivery history lives inside the invoice, not in the main menu. You need to open the invoice first:
Go to Sales invoices.
Click the invoice to open its details.
Open the Events tab.
The Events tab lists everything that happened to the document, most recent first.
Step 2: read the status
A delivery that is going well shows these entries:
"Delivery in progress via OpenPeppol" — the invoice is being sent.
"No errors. openpeppol: Delivery requested." — Peppol has accepted the invoice but has not confirmed receipt yet.
"No errors. openpeppol: Delivered to service." — the invoice was delivered.
Note: actual delivery to your customer can take several working days. "Delivery requested" is not a failure.
A failure looks like this:
"Delivery via OpenPeppol failed because openpeppol: Delivery to service failed. [fatal_error] [BR-CO-16] in [/:Invoice[1]] …"
The code in square brackets is the Peppol validation rule your invoice broke. If several codes are listed, you have to correct all of them before the invoice will go out.
Step 3: correct the error
Find your code below.
BR-CO-16
What it means: The amount due for payment (BT-115) does not equal the total with VAT (BT-112) minus the amount already paid (BT-113) plus rounding (BT-114).
How to fix it: Your totals do not add up. Open the invoice and check the amount due against the total including VAT. A difference of one cent is enough to block the send.
PEPPOL-EN16931-R008
What it means: The document must not contain empty elements.
How to fix it: A required field was left blank. Go through the invoice and fill in every mandatory field, including the PO number, which Peppol requires. Save and resend.
BR-CO-15
What it means: The total with VAT (BT-112) does not equal the total without VAT (BT-109) plus the total VAT (BT-110).
How to fix it: Check the VAT calculation on the invoice. The three totals must be consistent with each other.
BR-CL-24
What it means: The file type of an attachment is not allowed on a Peppol invoice.
How to fix it: Peppol only accepts these attachment types: PDF, PNG, JPEG, CSV, XLSX and ODS. Remove the offending attachment, or convert it to PDF and attach it again.
PEPPOL-EN16931-CL001
What it means: Same cause as BR-CL-24: the attachment's file type is outside the list Peppol accepts.
How to fix it: Remove the attachment or convert it to PDF.
BR-27 / BR-28
What it means: A unit price on an invoice line is negative.
How to fix it: Peppol does not allow negative unit prices. To invoice a negative amount, issue a credit note instead.
BR-25 / BR-16
What it means: Every invoice line must have an item name (BT-153), and the invoice must have at least one line.
How to fix it: Add a description to each line, and make sure the invoice has at least one line item.
BR-AE-02
What it means: A reverse-charge line requires both your VAT identifier (BT-31) and your customer's VAT identifier (BT-48).
How to fix it: Open the customer record and your own company details, and make sure both VAT numbers are filled in. Then resend.
BR-CO-09
What it means: A VAT identifier is missing its country prefix.
How to fix it: VAT numbers must start with the two-letter country code, for example BE0123456789. Correct it on the customer record or in your company details.
BR-CO-17 / BR-S-09
What it means: The VAT amount for a rate does not equal the taxable base multiplied by that rate.
How to fix it: Check the VAT rate applied to each line. This usually comes from a rounding difference or a manually overwritten VAT amount.
BR-55
What it means: A credit note does not reference the invoice it corrects.
How to fix it: Open the credit note and fill in the number of the original invoice.
PEPPOL-COMMON-R040
What it means: The GLN used as an electronic address is not a valid GS1 number.
How to fix it: Check the Peppol identifier on the customer record. If you do not use a GLN, use the company number or the VAT number instead.
The recipient cannot be reached on Peppol
If the failure says the recipient is not registered, the problem is the customer record rather than the invoice:
Check that your customer is actually on Peppol, in the Peppol Directory.
Check the identifier on the customer record in Customers & Suppliers. If your customer is registered under their company number rather than their VAT number, enter the company number in the VAT field.
If they are not on Peppol at all, send the invoice another way. See How to change the delivery channel of a customer.
Step 4: resend
After correcting the invoice, save it and send it again. Then reopen the Events tab to confirm the new attempt went through.
Still stuck?
Contact support and paste the complete error line from the Events tab, together with the invoice number. The full line contains the rule code and the exact field that failed, which lets the team answer without asking you for a screenshot first.