No seller tax identifier is provided
As soon as a VAT category S, Z, E, AE, K, G, L or M is used, at least one of `Seller VAT identifier` (BT-31), `Seller tax registration identifier` (BT-32) or the `SELLER TAX REPRESENTATIVE PARTY` group (BG-11) must be provided.
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
The rule covers nearly every useful category: as soon as an invoice carries VAT, an exemption or a reverse charge, it must say on whose behalf. Three routes are accepted and one is enough — many issuers fill in the intra-EU VAT number (BT-31) and need do nothing else.
How to fix it
Fill in the seller's tax identifier in your master data. Factlint does not infer it: naming the wrong tax entity on an invoice is not a mistake a tool should make on your behalf.