BR-AE-04 error EN 16931
BR-AE-04 — reverse charge without buyer VAT ID
What it means
Reverse charge (category AE) moves the VAT obligation to the buyer, so the buyer must be identifiable for VAT: their VAT identifier (BT-48) — or a tax registration identifier — is mandatory. Its pair BR-AE-02 requires the seller’s.
What triggers it
Any line or breakdown uses AE and the buyer has neither vatId nor taxRegistrationId.
How to fix it
Set the buyer’s VAT ID (and check it in VIES before invoicing):
{ "buyer": { "vatId": "DE123456789" } } An invalid buyer VAT ID invalidates the reverse charge itself, not just the XML. Free tool coming: /tools/vat-check/.
Check your invoice now. Paste it into the free validator — it flags BR-AE-04 and every other EN 16931, Peppol and XRechnung rule, each with the fix.
Or run the same check via API:
curl -X POST https://fakturwire.com/v1/validate \
-H "authorization: Bearer $FW_KEY" \
-d '{"invoice": { ... }, "profile": "en16931"}'