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).
ubl-creditnote:CreditNote[$SupplierCountry = 'IS' and $CustomerCountry = 'IS']/cac:AccountingCustomerParty | ubl-invoice:Invoice[$SupplierCountry = 'IS' and $CustomerCountry = 'IS']/cac:AccountingCustomerPartyexists(cac:Party/cac:PartyLegalEntity/cbc:CompanyID) and cac:Party/cac:PartyLegalEntity/cbc:CompanyID/@schemeID = '0196'