diff --git a/app/models/validations/sales/sale_information_validations.rb b/app/models/validations/sales/sale_information_validations.rb
index 9d65bc799..7cce2a590 100644
--- a/app/models/validations/sales/sale_information_validations.rb
+++ b/app/models/validations/sales/sale_information_validations.rb
@@ -77,7 +77,7 @@ module Validations::Sales::SaleInformationValidations
   def validate_discounted_ownership_value(record)
     return unless record.saledate && record.form.start_year_2024_or_later?
     return unless record.value && record.deposit && record.ownershipsch
-    return unless record.mortgage || record.mortgageused == 2 || record.mortgageused == 3
+    return unless record.mortgage || record.mortgageused == 2
     return unless record.discount || record.grant || record.type == 29
 
     tolerance = record.value_with_discount_tolerance
diff --git a/spec/models/validations/sales/sale_information_validations_spec.rb b/spec/models/validations/sales/sale_information_validations_spec.rb
index 7a4537322..4104823f0 100644
--- a/spec/models/validations/sales/sale_information_validations_spec.rb
+++ b/spec/models/validations/sales/sale_information_validations_spec.rb
@@ -703,6 +703,18 @@ RSpec.describe Validations::Sales::SaleInformationValidations do
         end
       end
     end
+
+    context "when mortgageused is don't know" do
+      let(:record) { FactoryBot.build(:sales_log, :saledate_today, mortgageused: 3, deposit: 10_000, value: 100_000, discount: 10, ownershipsch: 2, type: 9) }
+
+      it "does not add an error" do
+        sale_information_validator.validate_discounted_ownership_value(record)
+        expect(record.errors["mortgage"]).to be_empty
+        expect(record.errors["value"]).to be_empty
+        expect(record.errors["deposit"]).to be_empty
+        expect(record.errors["discount"]).to be_empty
+      end
+    end
   end
 
   describe "#validate_outright_sale_value_matches_mortgage_plus_deposit" do