What it means
Every amount in a Peppol invoice must carry the invoice currency (BT-5) in its currencyID attribute. The only exception is the VAT total in accounting currency (BT-111), which carries the VAT accounting currency.
Why it matters
Peppol BIS Billing 3.0 adds this rule to EN 16931 so that every access point and receiver can process the invoice the same way. The sending or receiving access point rejects an invoice that fails it, so it never reaches the buyer.
How to fix it
Make sure the whole invoice is in one currency: set the invoice currency in your invoicing software and check that no line or price was entered in another one. If you build the XML yourself, write the same currencyID on every amount, and use the other currency only on the second cbc:TaxAmount in the extra cac:TaxTotal.
The rule as published
Read the rule on the publisher's site
Business terms: BT-5, BT-111
Where this rule applies
| Rule set | Version |
|---|---|
| Peppol BIS Billing 3.0 (invoice) | 2026.5 |
| Peppol BIS Billing 3.0 (credit note) | 2026.5 |
Check your file
Drop your e-invoice to see whether PEPPOL-EN16931-R051 still fails, and which other rules do.