DIFI (authorities) defines the Contact ID: The customer contact, known as “Deres ref” in Norwegian, is mandatory. The element is used for the reference of who ordered the products/services.
The validation rules on eInvoice from DIFI will be updated 23rd May in order to handle foreign IBAN numbers. The rules apply to EHF Invoice and Credit note 2.0.5. Ref. https://vefa.difi.no/ehf/announcement/2016-02-02-hotfix-of-iban-rule/ This apply to company bank account IBAN number in AX.