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E-Invoice Validator

CIUS

A country-specific or network-specific tightening of EN 16931.

CIUS stands for Core Invoice Usage Specification: a specification that adopts and supplements EN 16931 - usually with additional mandatory fields.

Peppol BIS Billing 3.0 and XRechnung are the best-known CIUS. An invoice can meet EN 16931 and still fail due to a CIUS.

The CIUS is determined via BT-24. That's exactly why a useful validator checks it: EN 16931 alone is not a guarantee that the invoice will arrive.

Rules that often fail here

See also

Status: 12.10.2026