fatal UBL
[PEPPOL-EN16931-P0108]-Tax Category E MUST be used when exemption reason code is VATEX-EU-D
cac:TaxCategory[upper-case(cbc:TaxExemptionReasonCode)='VATEX-EU-D']
normalize-space(cbc:ID)='E'
Source: Peppol BIS Billing 3.0 Schematron, UBL (OpenPeppol, docs.peppol.eu validation artefacts 3.0.21).
Invoice XML (UBL 2.1 Invoice/CreditNote or UN/CEFACT CII D16B, max 5 MB):
Validate