BR-CO-04
A rule of the European standard EN 16931 – applies to every invoice following the standard, including Peppol BIS Billing 3.0.
What this error means
BR-CO-04
An invoice line has no VAT category (BT-151).
How to fix it
Assign each line a VAT category code: S (standard), Z (zero), E (exempt), AE (reverse charge), K, G or O.