Why does EN 16931 only allow format 102 for CII dates?

EN 16931 narrows CII to a single date format so every receiver across Europe interprets dates identically.

Is this error safe to auto-fix?

Yes. Converting ISO 8601 to CCYYMMDD is deterministic and reversible, and format="102" is the only permitted value. Invoice Navigator applies this fix automatically.

Does this apply to all date elements?

Yes — IssueDateTime, DeliveryChainEvent/OccurrenceDateTime, BillingSpecifiedPeriod boundaries, DueDateDateTime, and document reference issue dates.

What if my software outputs full ISO 8601 timestamps?

Strip the time component. EN 16931 CII dates are date-only.

Does this error block ZUGFeRD 2.x and Factur-X submissions?

Yes. EN 16931 Schematron is enforced for ZUGFeRD 2.x and Factur-X from BASIC upwards.

Error codes · cii-d16b

CII-DT-024Fixable here

ReferenceTypeCode element must not be present

This is the rejection, word for word: „[CII-DT-024] CII-DT-024 is an EN 16931 assertion on the CII binding. The element ram:ReferenceTypeCode must not be present in date/time structures.“

What to have readyThe missing value from your purchase order, contract or bookkeeping.

What we doConvert every CII date to eight-digit CCYYMMDD and add format="102" on the udt element.

Choose the rejected invoiceor drop it here

XRechnung XML or ZUGFeRD PDF. Checking is free · corrected file €1.90 · the first every 30 days is free · no sign-up.

If you enter it yourself in your invoicing software

Before

<ram:IssueDateTime><udt:DateTimeString>2026-04-20</udt:DateTimeString></ram:IssueDateTime>

After

<ram:IssueDateTime><udt:DateTimeString format="102">20260420</udt:DateTimeString></ram:IssueDateTime>

What the finding looks likeExample

FindingValue missing · CII-DT-024

From youThe missing value

ThenPassed

ProofSHA-256 and /verify link after the check