Validation rules

NB-IBAN-CHECKSUM — normbill pre-flight check

The IBAN fails its checksum — this is almost certainly a typo.

Rule: NB-IBAN-CHECKSUM — normbill pre-flight check (no single official rule id applies)
Severity: warning
Business term: BT-84 — Payment account IBAN
Field in your JSON: invoice.payment.iban

How to fix it

Double-check invoice.payment.iban or invoice.payment.debited_iban against your bank details.

NB-IBAN-CHECKSUM auf Deutsch — was bedeutet der Fehler?

Die IBAN besteht die Prüfziffernkontrolle nicht — mit hoher Wahrscheinlichkeit ein Tippfehler.

So beheben Sie den Fehler

Gleichen Sie invoice.payment.iban oder invoice.payment.debited_iban mit Ihren Bankdaten ab.

NB-* checks run before generation to catch problems the official rule set would only report indirectly. The authoritative KoSIT validation still has the final word on conformance.

Related rules

BR-DE-23-a — Payment means is a credit transfer (code 30/58) but no payment account (IBAN, BT-84) is given.
BR-DE-25-b — Payment means is a SEPA direct debit (code 59), so a payee account (BG-17) must not be present. normbill…
BR-50 — A credit-transfer payment account is present but its account identifier (IBAN, BT-84) is empty.
BR-61 — The payment means is a credit transfer (code 30 or 58), so a payment account identifier (IBAN, BT-84) is…
BR-DE-19 — The payment account identifier (BT-84) does not look like a valid IBAN — for SEPA credit transfers (means…

Official sources

Every 422 from the API lists the rule id, the path in your request JSON, a plain-language message and a suggested fix — see the docs overview for the report format.

Or try it live: drop any XRechnung XML on the free validator — same KoSIT-backed report, no account.