What it means
In a UBL invoice or credit note, the seller (BG-4) has a postal address (BG-5) under cac:AccountingSupplierParty/cac:Party/cac:PostalAddress. This rule checks that this address has no cbc:InhouseMail, a text that routes post inside a building, such as a mail stop or internal mailbox.
Why it matters
This is a warning, so the file is still accepted. The EN 16931 address has no field for internal mail routing, so the recipient's software normally ignores it. It is worth fixing when you want a clean file, or when a recipient asks for invoices without warnings.
How to fix it
Switch off any export option that adds an internal mail code to the seller address, then export again. The street, city, post code and country stay as they are. If you build the XML yourself, delete cbc:InhouseMail from cac:PostalAddress in the seller block. If the detail matters to the buyer, add it to an address line.
The rule as published
A UBL invoice should not include the AccountingSupplierParty Party PostalAddress InhouseMail 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-CR-156 still fails, and which other rules do.