PEPPOL-EN16931-F001
A date MUST be formatted YYYYMMDD.
What does this rule mean?
A date is not formatted as YYYYMMDD.
In the CII syntax Peppol requires the basic format without separators (format="102").
Official rule message (standard)
A date MUST be formatted YYYYMMDD.
Where the rule applies
Syntax: CII · UBL
The same rule, expressed twice: UBL and CII name the same fields with different paths. Running a CII file against the UBL rules is why you get errors that mean nothing.
UBL
cbc:IssueDate | cbc:DueDate | cbc:TaxPointDate | cbc:StartDate | cbc:EndDate | cbc:ActualDeliveryDate
CII
udt:DateTimeString
Technical test
The rule passes when this Schematron expression holds true:
normalize-space(@format) = '102' and string-length(text()) = 8 and matches(normalize-space(text()), '20[0-9]{6}')How to fix it
A missing or incorrect business entry only you can supply. Add or correct it, then re-check.
Write the date as 20260811 rather than 2026-08-11.
Correct the affected entry in your XML, then re-check the invoice. Validation runs locally in your browser — your file never leaves your machine.
Check an e-invoice here
Drop an XML or ZUGFeRD PDF file here. Validation runs locally in your browser against EN 16931 — your file never leaves your machine.