diff --git a/addons/account_edi_ubl_cii/i18n/account_edi_ubl_cii.pot b/addons/account_edi_ubl_cii/i18n/account_edi_ubl_cii.pot
index a6531a09fdd..72c37e67ead 100644
--- a/addons/account_edi_ubl_cii/i18n/account_edi_ubl_cii.pot
+++ b/addons/account_edi_ubl_cii/i18n/account_edi_ubl_cii.pot
@@ -785,6 +785,13 @@ msgid ""
 "the form: NO179728982MVA."
 msgstr ""
 
+#. module: account_edi_ubl_cii
+#. odoo-python
+#: code:addons/account_edi_ubl_cii/models/account_edi_xml_ubl_bis3.py:0
+#, python-format
+msgid "The VAT of the %s should be prefixed with its country code."
+msgstr ""
+
 #. module: account_edi_ubl_cii
 #. odoo-python
 #: code:addons/account_edi_ubl_cii/models/account_edi_xml_cii_facturx.py:0
diff --git a/addons/account_edi_ubl_cii/models/account_edi_xml_ubl_bis3.py b/addons/account_edi_ubl_cii/models/account_edi_xml_ubl_bis3.py
index 4ff48152d02..0d30c92e62b 100644
--- a/addons/account_edi_ubl_cii/models/account_edi_xml_ubl_bis3.py
+++ b/addons/account_edi_ubl_cii/models/account_edi_xml_ubl_bis3.py
@@ -59,10 +59,14 @@ class AccountEdiXmlUBLBIS3(models.AbstractModel):
             vals.pop('registration_name', None)
             vals.pop('registration_address_vals', None)
 
-            # /!\ For Australian companies, the ABN is encoded on the VAT field, but doesn't have the 2 digits prefix,
-            # causing a validation error
-            if partner.country_id.code == "AU" and partner.vat and not partner.vat.upper().startswith("AU"):
-                vals['company_id'] = "AU" + partner.vat
+            # Some extra european countries use Bis 3 but do not prepend their VAT with the country code (i.e.
+            # Australia). Allow them to use Bis 3 without raising BR-CO-09.
+            if (
+                partner.country_id
+                and partner.country_id not in self.env.ref('base.europe').country_ids
+                and not partner.vat[:2].isalpha()
+            ):
+                vals['company_id'] = partner.country_id.code + partner.vat
 
         # sources:
         #  https://anskaffelser.dev/postaward/g3/spec/current/billing-3.0/norway/#_applying_foretaksregisteret
@@ -327,6 +331,19 @@ class AccountEdiXmlUBLBIS3(models.AbstractModel):
                 # /!\ exception: possible to have any number of ecotaxes (fixed tax) with a regular percentage tax
                 constraints.update({'cen_en16931_tax_line': _("Each invoice line shall have one and only one tax.")})
 
+        for role in ('supplier', 'customer'):
+            scheme_vals = vals['vals'][f'accounting_{role}_party_vals']['party_vals']['party_tax_scheme_vals'][-1:]
+            if (
+                not (scheme_vals and scheme_vals[0]['company_id'] and scheme_vals[0]['company_id'][:2].isalpha())
+                and (scheme_vals and scheme_vals[0]['tax_scheme_vals'].get('id') == 'VAT')
+                and self._name in ('account.edi.xml.ubl_bis3', 'account.edi.xml.ubl_nl', 'account.edi.xml.ubl_de')
+            ):
+                # [BR-CO-09]-The Seller VAT identifier (BT-31), the Seller tax representative VAT identifier (BT-63)
+                # and the Buyer VAT identifier (BT-48) shall have a prefix in accordance with ISO code ISO 3166-1
+                # alpha-2 by which the country of issue may be identified. Nevertheless, Greece may use the prefix ‘EL’.
+                constraints.update({f'cen_en16931_{role}_vat_country_code': _(
+                    "The VAT of the %s should be prefixed with its country code.", role)})
+
         return constraints
 
     def _invoice_constraints_peppol_en16931_ubl(self, invoice, vals):