diff --git a/app/services/bulk_upload/lettings/year2024/row_parser.rb b/app/services/bulk_upload/lettings/year2024/row_parser.rb
index 077e1ac0f..8fc7ea564 100644
--- a/app/services/bulk_upload/lettings/year2024/row_parser.rb
+++ b/app/services/bulk_upload/lettings/year2024/row_parser.rb
@@ -421,6 +421,7 @@ class BulkUpload::Lettings::Year2024::RowParser
   validate :validate_owning_org_data_given, on: :after_log
   validate :validate_owning_org_exists, on: :after_log
   validate :validate_owning_org_owns_stock, on: :after_log
+  validate :validate_owning_org_affiliated, on: :after_log
   validate :validate_owning_org_permitted, on: :after_log
 
   validate :validate_managing_org_data_given, on: :after_log
@@ -897,8 +898,6 @@ private
 
   def validate_owning_org_permitted
     return unless owning_organisation
-
-    bulk_upload_organisation = bulk_upload.user.support? ? Organisation.find(bulk_upload.organisation_id) : bulk_upload.user.organisation
     return if bulk_upload_organisation.affiliated_stock_owners.include?(owning_organisation)
 
     block_log_creation!
@@ -908,6 +907,18 @@ private
     end
   end
 
+  def validate_owning_org_affiliated
+    return unless owning_organisation
+    return unless bulk_upload.user.support?
+    return if bulk_upload_organisation.affiliated_stock_owners.include?(owning_organisation)
+
+    block_log_creation!
+
+    if errors[:field_1].blank?
+      errors.add(:field_1, "This owning organisation is not affiliated with #{bulk_upload_organisation.name}", category: :setup)
+    end
+  end
+
   def validate_all_charges_given
     return if supported_housing? && field_125 == 1
 
@@ -1633,4 +1644,8 @@ private
   def reason_is_other?
     field_98 == 20
   end
+
+  def bulk_upload_organisation
+    Organisation.find(bulk_upload.organisation_id)
+  end
 end
diff --git a/app/services/bulk_upload/sales/year2024/row_parser.rb b/app/services/bulk_upload/sales/year2024/row_parser.rb
index 1f6386464..df11b2a6a 100644
--- a/app/services/bulk_upload/sales/year2024/row_parser.rb
+++ b/app/services/bulk_upload/sales/year2024/row_parser.rb
@@ -458,6 +458,7 @@ class BulkUpload::Sales::Year2024::RowParser
   validate :validate_owning_org_data_given, on: :after_log
   validate :validate_owning_org_exists, on: :after_log
   validate :validate_owning_org_owns_stock, on: :after_log
+  validate :validate_owning_org_affiliated, on: :after_log
   validate :validate_owning_org_permitted, on: :after_log
 
   validate :validate_assigned_to_exists, on: :after_log
@@ -1302,8 +1303,6 @@ private
 
   def validate_owning_org_permitted
     return unless owning_organisation
-
-    bulk_upload_organisation = bulk_upload.user.support? ? Organisation.find(bulk_upload.organisation_id) : bulk_upload.user.organisation
     return if bulk_upload_organisation.affiliated_stock_owners.include?(owning_organisation)
 
     block_log_creation!
@@ -1313,6 +1312,18 @@ private
     end
   end
 
+  def validate_owning_org_affiliated
+    return unless owning_organisation
+    return unless bulk_upload.user.support?
+    return if bulk_upload_organisation.affiliated_stock_owners.include?(owning_organisation)
+
+    block_log_creation!
+
+    if errors[:field_1].blank?
+      errors.add(:field_1, "This owning organisation is not affiliated with #{bulk_upload_organisation.name}", category: :setup)
+    end
+  end
+
   def validate_assigned_to_exists
     return if field_3.blank?
 
@@ -1500,4 +1511,8 @@ private
   def valid_nationality_options
     %w[0] + GlobalConstants::COUNTRIES_ANSWER_OPTIONS.keys # 0 is "Prefers not to say"
   end
+
+  def bulk_upload_organisation
+    Organisation.find(bulk_upload.organisation_id)
+  end
 end