What it means
Every element whose name ends in BinaryObject must have a mimeCode attribute. For an embedded attachment (BT-125), this is normally the mimeCode attribute (BT-125-1) on cbc:EmbeddedDocumentBinaryObject, with a value such as application/pdf for a PDF or image/png for a PNG image. This check tests only whether the attribute exists, not whether its value is non-empty, correct for the file or permitted by another rule.
Why it matters
The MIME code identifies the attachment's media type. EN 16931 requires the attribute on binary object elements.
How to fix it
Add mimeCode to the affected binary object element. For a PDF attachment in cbc:EmbeddedDocumentBinaryObject, use mimeCode="application/pdf". If you use invoicing software, ask its supplier to include the attribute in the export. If you do not need the attachment, remove it and export again. Recheck the file.
Once the file is corrected, check it again for free: Validate an invoice against EN 16931
Or fix the invoice in a form and download the corrected file, for 1 credit: Fix a rejected e-invoice
The rule as published
Binary object elements shall contain the mime code attribute Where this rule applies
| Rule set | Version |
|---|---|
| EN 16931 (UBL) | 1.3.17 |
| EN 16931 (UBL credit note) | 1.3.17 |
| XRechnung 3.0 (UBL) | 3.0.2 |
| XRechnung 3.0 (UBL credit note) | 3.0.2 |
| Peppol BIS Billing 3.0 (invoice) | 2026.5 |
| Peppol BIS Billing 3.0 (credit note) | 2026.5 |
| SI-UBL 2.0 / NLCIUS (invoice) | 2.0.3.13 |
| SI-UBL 2.0 / NLCIUS (credit note) | 2.0.3.13 |
| France CTC (UBL invoice) | 1.4.0-04 |
| France CTC (UBL credit note) | 1.4.0-04 |
| CIUS-RO UBL Invoice 1.0.9 | 1.0.9 |
| CIUS-RO UBL Credit Note 1.0.9 | 1.0.9 |
Check your file
Drop your e-invoice to see whether UBL-DT-06 still fails, and which other rules do.