Fixture ID: allowanceRated_K · XPath: /ubl:Invoice/cac:AllowanceCharge[2]/cac:TaxCategory/cbc:Percent
The document level charge at charges[0] uses VAT category K (Intra-community supply), so its VAT rate (BT-103) must be 0 (zero), but it is 19. The supply is zero-rated on despatch and acquired VAT is due from the customer in the destination member state at that state's rate. Quoting a rate here would assert a tax liability that arises in a jurisdiction this invoice does not settle.
BR-IC-07Set charges[0].vatRate to 0, or omit it — this library normalises the rate for category K either way. If you did mean to charge 19% VAT on this charge, the category should be S instead, and that will change which breakdown group it nets into.
"vatCategory": "K", "vatRate": 0