diff --git a/lib/secretariat/trade_party.rb b/lib/secretariat/trade_party.rb
index 8ad0125..2105257 100644
--- a/lib/secretariat/trade_party.rb
+++ b/lib/secretariat/trade_party.rb
@@ -21,8 +21,19 @@ module Secretariat
     :id,
     :name, :street1, :street2, :city, :postal_code, :country_id, :vat_id, :global_id, :global_id_scheme_id, :tax_id,
     :person_name, :legal_organization,
+    :contact_name, :contact_phone, :contact_email,
     keyword_init: true,
   ) do
+    # BG-6 / BG-9 contact. contact_name is the fork's name for upstream's
+    # person_name (BT-56); both feed the single DefinedTradeContact element.
+    def contact?
+      contact_person_name.present? || contact_phone.present? || contact_email.present?
+    end
+
+    def contact_person_name
+      contact_name.present? ? contact_name : person_name
+    end
+
     def to_xml(xml, exclude_tax: false, version: 2)
       if id && !exclude_tax
         xml['ram'].ID id # BT-46
@@ -40,9 +51,22 @@ def to_xml(xml, exclude_tax: false, version: 2)
           end
         end
       end
-      if person_name
+      if version == 2 && contact?
+        # EN16931 BG-6 SELLER CONTACT (required by XRechnung CIUS rule BR-DE-2)
         xml['ram'].DefinedTradeContact do
-          xml['ram'].PersonName person_name
+          if contact_person_name.present?
+            xml['ram'].PersonName contact_person_name
+          end
+          if contact_phone.present?
+            xml['ram'].TelephoneUniversalCommunication do
+              xml['ram'].CompleteNumber contact_phone
+            end
+          end
+          if contact_email.present?
+            xml['ram'].EmailURIUniversalCommunication do
+              xml['ram'].URIID contact_email
+            end
+          end
         end
       end
       xml['ram'].PostalTradeAddress do
diff --git a/test/invoice_test.rb b/test/invoice_test.rb
index 8af2c76..5242786 100644
--- a/test/invoice_test.rb
+++ b/test/invoice_test.rb
@@ -291,7 +291,10 @@ def make_de_invoice
         city: 'Hamburg',
         postal_code: '20253',
         country_id: 'DE',
-        vat_id: 'DE304755032'
+        vat_id: 'DE304755032',
+        contact_name: 'Depfu Buchhaltung',
+        contact_phone: '+49 40 123456',
+        contact_email: 'billing@depfu.com'
       )
       buyer = TradeParty.new(
         name: 'Depfu inc',
@@ -709,6 +712,16 @@ def test_simple_eu_invoice_with_attachment_against_schematron
       assert_equal [], errors
     end
 
+    def test_seller_contact_is_rendered_for_v2
+      xml = make_de_invoice.to_xml(version: 2)
+      doc = Nokogiri::XML(xml)
+      contact = doc.at_xpath('//ram:SellerTradeParty/ram:DefinedTradeContact', 'ram' => 'urn:un:unece:uncefact:data:standard:ReusableAggregateBusinessInformationEntity:100')
+      assert contact, 'expected DefinedTradeContact to be rendered'
+      assert_equal 'Depfu Buchhaltung', contact.at_xpath('ram:PersonName', 'ram' => 'urn:un:unece:uncefact:data:standard:ReusableAggregateBusinessInformationEntity:100').text
+      assert_equal '+49 40 123456', contact.at_xpath('ram:TelephoneUniversalCommunication/ram:CompleteNumber', 'ram' => 'urn:un:unece:uncefact:data:standard:ReusableAggregateBusinessInformationEntity:100').text
+      assert_equal 'billing@depfu.com', contact.at_xpath('ram:EmailURIUniversalCommunication/ram:URIID', 'ram' => 'urn:un:unece:uncefact:data:standard:ReusableAggregateBusinessInformationEntity:100').text
+    end
+
     def test_simple_de_invoice_v2
       xml = make_de_invoice.to_xml(version: 2)
       v = Validator.new(xml, version: 2)