CDS12170 — Authorisation Error: Invalid VAT number. Please note, if you are attempting to claim Onward Supply Relief (OSR), you must be identified as trading under the terms of the Northern Ireland Protocol (now Windsor Framework) for VAT.

Two elements, or a value and a rule, disagree. Read both elements together: completing one element with a particular code often requires another value, and the fault is frequently in the element you did not change. The family also covers parties and authorisations that are not recognised, references that must be unique, and messages sent out of sequence.