BT-47Buyer legal registration identifier
Official rule text
[IS-R-004] If seller and buyer are icelandic then the invoice shall contain the buyers icelandic legal identifier — Ef seljandi og kaupandi eru íslenskir þá skal reikningurinn innihalda íslenska kennitölu kaupanda (BT-47).
Why this error occurs
This rule only applies when another field has a certain value (for example a payment means code or an invoice type). Your file triggers the condition but does not provide the data that then becomes mandatory, or provides data that is then forbidden.
How to fix it
Either change the triggering value so the condition no longer applies, or add/remove the dependent elements as the rule text describes. Check the condition in the XPath test above to see exactly which value triggers it.
What the validator checks
Checked element (context):
UBL
ubl-creditnote:CreditNote[$SupplierCountry = 'IS' and $CustomerCountry = 'IS']/cac:AccountingCustomerParty | ubl-invoice:Invoice[$SupplierCountry = 'IS' and $CustomerCountry = 'IS']/cac:AccountingCustomerPartyTest (XPath):
exists(cac:Party/cac:PartyLegalEntity/cbc:CompanyID) and cac:Party/cac:PartyLegalEntity/cbc:CompanyID/@schemeID = '0196'Check your invoice
Drop your XML or PDF on the validator and every failed rule is linked to its page here. Free, no account, the file is not stored.
Same check via API:
curl -F file=@invoice.xml https://einvoicechecker.com/v1/validateRelated rules
IS-R-001If seller is icelandic then invoice type should be 380 or 381 — Ef seljandi er…IS-R-002If seller is icelandic then it shall contain sellers legal id — Ef seljandi er…IS-R-003If seller is icelandic then it shall contain his address with street name and zip code…IS-R-005If seller and buyer are icelandic then the invoice shall contain the buyers address…IS-R-006If seller is icelandic and payment means code is 9 then a 12 digit account id must…IS-R-007If seller is icelandic and payment means code is 42 then a 12 digit account id must…IS-R-008If seller is icelandic and invoice contains supporting description EINDAGI then the id…IS-R-009If seller is icelandic and invoice contains supporting description EINDAGI invoice…
Frequently asked questions
What does IS-R-004 mean?
IS-R-004 is a peppol national rule: If seller and buyer are icelandic then the invoice shall contain the buyers icelandic legal identifier — Ef seljandi og kaupandi eru íslenskir þá skal reikningurinn innihalda íslenska kennitölu kaupanda (BT-47).
Will my invoice be rejected because of IS-R-004?
Yes. IS-R-004 is flagged "fatal"; validators (KoSIT, Peppol access points, the German ZRE/OZG-RE portals, KSeF) reject the invoice until it is fixed.
Which formats does IS-R-004 apply to?
Only when the seller (or for some rules the buyer) is in the named country: the rule is triggered by the country code of the party. Dutch rules implement NLCIUS, German rules the XRechnung requirements inside Peppol. Syntax: UBL.
Source: Peppol BIS Billing 3.0.20 national rules (November 2025). Catalogue generated from the official rule sets on 2026-10-15.