The invoice type code is not in the expected list
`Invoice type code` (BT-3) should be 326, 380, 381, 384, 389, 875, 876 or 877 from the UNTDID 1001 code list.
Only the issuer holds this value: Factlint reports it and never fabricates it. Test your invoice to find out whether it is affected.
Why this error happens
XRechnung narrows a list that EN 16931 leaves wide. The last three codes — 875, 876, 877 — are specific to German construction (interim and final construction invoices). A code that is technically valid but outside the list, such as 388 (*tax invoice*), passes European validation and stops here.
How to fix it
Pick the code that actually describes the document in your system. Factlint does not replace it: an invoice type is a legal qualification, not a formatting detail — turning a 388 into a 380 would change what the document claims to be.