IN-CUSTOMIZATION-FORMAT:CustomizationID format recommendation
Fix: Replace with standard Peppol BIS 3.0 CustomizationID Upload your invoice to fix this automatically.
CustomizationID should follow Peppol BIS Billing 3.0 format
Engine Classification
Structural normalization · No financial impact · Safe deterministic remediation
What is IN-CUSTOMIZATION-FORMAT?
IN-CUSTOMIZATION-FORMAT is a warning validation rule defined in the Peppol BIS 3.0 specification. It validates the CustomizationID element in the UBL invoice XML.
The invoice may pass transmission, but this non-compliance can cause problems during tax audits or buyer-side processing.
Target path: /Invoice/cbc:CustomizationID
Why This Error Matters
CustomizationID determines which validation rules apply to the invoice.
IN-CUSTOMIZATION-FORMAT is a soft failure that can cause issues at the receiving end — tax audits, ERP processing, or VAT reconciliation mismatches.
Invoice Navigator can automatically correct this error in your pipeline. The fix is applied with full audit evidence, so your compliance trail remains intact.
Validator Behavior
- ·Generates validation warning
- ·Rejected by PEPPOL Access Points
- ·Error returned: IN-CUSTOMIZATION-FORMAT
- ·Specification: Peppol BIS 3.0
How to Fix It
Set CustomizationID
urn:cen.eu:en16931:2017#compliant#urn:fdc:peppol.eu:2017:poacc:billing:3.0
For credit notes
Same identifier applies
Country extensions
May need additional extension for country-specific rules
Before / After
<Invoice> <cbc:CustomizationID><!-- invalid or missing value --></cbc:CustomizationID> </Invoice>
<Invoice> <cbc:CustomizationID>correct-value</cbc:CustomizationID> </Invoice>
Technical Reference
/Invoice/cbc:CustomizationIDCode Example
<cbc:CustomizationID>urn:cen.eu:en16931:2017#compliant#urn:fdc:peppol.eu:2017:poacc:billing:3.0</cbc:CustomizationID>Common Causes
- ·Wrong specification ID
- ·Using EN16931 only
- ·Outdated Peppol version
Seeing this in production? The API handles IN-CUSTOMIZATION-FORMAT automatically. See the fix response →
Commonly Seen In
Frequently Asked Questions
The CustomizationID must match the Peppol BIS 3.0 specification identifier.
Use the correct Peppol BIS 3.0 CustomizationID. Invoice Navigator can help identify and fix this issue.
Yes, PEPPOL-EN16931-R002 is a critical error that must be fixed.
Related Errors
Related Content
Last updated: 27 February 2026
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