diff --git a/app/models/validations/sales/sale_information_validations.rb b/app/models/validations/sales/sale_information_validations.rb
index be0295f2c..c438e7f18 100644
--- a/app/models/validations/sales/sale_information_validations.rb
+++ b/app/models/validations/sales/sale_information_validations.rb
@@ -38,4 +38,17 @@ module Validations::Sales::SaleInformationValidations
       record.errors.add :fromprop, I18n.t("validations.sale_information.previous_property_type.property_type_bedsit")
     end
   end
+
+  def validate_discounted_ownership_value(record)
+    return unless record.mortgage && record.value && record.deposit && record.ownershipsch && (record.discount || record.grant)
+
+    discount_amount = record.discount ? record.value * record.discount / 100 : 0
+    grant_amount = record.grant || 0
+    value_with_discount = (record.value - discount_amount)
+    if record.mortgage + record.deposit + grant_amount != value_with_discount && record.discounted_ownership_sale?
+      %i[mortgage deposit grant value discount ownershipsch].each do |field|
+        record.errors.add field, I18n.t("validations.sale_information.discounted_ownership_value", value_with_discount: sprintf("%.2f", value_with_discount))
+      end
+    end
+  end
 end
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 0be594420..98f6b46de 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -425,6 +425,7 @@ en:
         property_type_bedsit: "Bedsit bedroom maximum 1"
       previous_property_type:
         property_type_bedsit: "A bedsit can not have more than 1 bedroom"
+      discounted_ownership_value: "Mortgage, deposit, grant and cash discount total must equal £%{value_with_discount}"
 
   soft_validations:
     net_income:
diff --git a/spec/models/validations/sales/sale_information_validations_spec.rb b/spec/models/validations/sales/sale_information_validations_spec.rb
index fb3aea06c..bdc3add7d 100644
--- a/spec/models/validations/sales/sale_information_validations_spec.rb
+++ b/spec/models/validations/sales/sale_information_validations_spec.rb
@@ -218,4 +218,108 @@ RSpec.describe Validations::Sales::SaleInformationValidations do
       end
     end
   end
+
+  describe "#validate_discounted_ownership_value" do
+    context "when mortgage, deposit and grant total does not equal market value - discount" do
+      let(:record) { FactoryBot.build(:sales_log, mortgage: 10_000, deposit: 5_000, grant: 3_000, value: 30_000, discount: 10, ownershipsch: 2) }
+
+      it "does not add an error" do
+        sale_information_validator.validate_discounted_ownership_value(record)
+
+        expect(record.errors[:mortgage]).to include(I18n.t("validations.sale_information.discounted_ownership_value", value_with_discount: "27000.00"))
+        expect(record.errors[:deposit]).to include(I18n.t("validations.sale_information.discounted_ownership_value", value_with_discount: "27000.00"))
+        expect(record.errors[:grant]).to include(I18n.t("validations.sale_information.discounted_ownership_value", value_with_discount: "27000.00"))
+        expect(record.errors[:value]).to include(I18n.t("validations.sale_information.discounted_ownership_value", value_with_discount: "27000.00"))
+        expect(record.errors[:discount]).to include(I18n.t("validations.sale_information.discounted_ownership_value", value_with_discount: "27000.00"))
+      end
+    end
+
+    context "when mortgage, deposit and grant total equals market value - discount" do
+      let(:record) { FactoryBot.build(:sales_log, mortgage: 10_000, deposit: 5_000, grant: 3_000, value: 20_000, discount: 10, ownershipsch: 2) }
+
+      it "does not add an error" do
+        sale_information_validator.validate_discounted_ownership_value(record)
+
+        expect(record.errors).to be_empty
+      end
+    end
+
+    context "when mortgage value is not provided" do
+      let(:record) { FactoryBot.build(:sales_log, mortgage: nil, deposit: 5_000, grant: 3_000, value: 20_000, discount: 10, ownershipsch: 2) }
+
+      it "does not add an error" do
+        sale_information_validator.validate_discounted_ownership_value(record)
+
+        expect(record.errors).to be_empty
+      end
+    end
+
+    context "when deposit value is not provided" do
+      let(:record) { FactoryBot.build(:sales_log, mortgage: 10_000, deposit: nil, grant: 3_000, value: 20_000, discount: 10, ownershipsch: 2) }
+
+      it "does not add an error" do
+        sale_information_validator.validate_discounted_ownership_value(record)
+
+        expect(record.errors).to be_empty
+      end
+    end
+
+    context "when grant value is not provided and discount is provided" do
+      let(:record) { FactoryBot.build(:sales_log, mortgage: 10_000, deposit: 5_000, grant: nil, value: 20_000, discount: 10, ownershipsch: 2) }
+
+      it "adds an error for invalid values" do
+        sale_information_validator.validate_discounted_ownership_value(record)
+
+        expect(record.errors[:mortgage]).to include(I18n.t("validations.sale_information.discounted_ownership_value", value_with_discount: "18000.00"))
+        expect(record.errors[:deposit]).to include(I18n.t("validations.sale_information.discounted_ownership_value", value_with_discount: "18000.00"))
+        expect(record.errors[:grant]).to include(I18n.t("validations.sale_information.discounted_ownership_value", value_with_discount: "18000.00"))
+        expect(record.errors[:value]).to include(I18n.t("validations.sale_information.discounted_ownership_value", value_with_discount: "18000.00"))
+        expect(record.errors[:discount]).to include(I18n.t("validations.sale_information.discounted_ownership_value", value_with_discount: "18000.00"))
+      end
+    end
+
+    context "when discount is not provided and grant is provided" do
+      let(:record) { FactoryBot.build(:sales_log, mortgage: 10_000, deposit: 5_000, grant: 1002, value: 20_000, discount: nil, ownershipsch: 2) }
+
+      it "adds an error for invalid values" do
+        sale_information_validator.validate_discounted_ownership_value(record)
+
+        expect(record.errors[:mortgage]).to include(I18n.t("validations.sale_information.discounted_ownership_value", value_with_discount: "20000.00"))
+        expect(record.errors[:deposit]).to include(I18n.t("validations.sale_information.discounted_ownership_value", value_with_discount: "20000.00"))
+        expect(record.errors[:grant]).to include(I18n.t("validations.sale_information.discounted_ownership_value", value_with_discount: "20000.00"))
+        expect(record.errors[:value]).to include(I18n.t("validations.sale_information.discounted_ownership_value", value_with_discount: "20000.00"))
+        expect(record.errors[:discount]).to include(I18n.t("validations.sale_information.discounted_ownership_value", value_with_discount: "20000.00"))
+      end
+    end
+
+    context "when value is not provided" do
+      let(:record) { FactoryBot.build(:sales_log, mortgage: 10_000, deposit: 5_000, grant: 3_000, value: nil, discount: 10, ownershipsch: 2) }
+
+      it "does not add an error" do
+        sale_information_validator.validate_discounted_ownership_value(record)
+
+        expect(record.errors).to be_empty
+      end
+    end
+
+    context "when discount and grant is not provided" do
+      let(:record) { FactoryBot.build(:sales_log, mortgage: 10_000, deposit: 5_000, grant: nil, value: 20_000, discount: nil, ownershipsch: 2) }
+
+      it "does not add an error" do
+        sale_information_validator.validate_discounted_ownership_value(record)
+
+        expect(record.errors).to be_empty
+      end
+    end
+
+    context "when owhership is not discounted" do
+      let(:record) { FactoryBot.build(:sales_log, mortgage: 10_000, deposit: 5_000, grant: 3_000, value: 20_000, discount: 10, ownershipsch: 1) }
+
+      it "does not add an error" do
+        sale_information_validator.validate_discounted_ownership_value(record)
+
+        expect(record.errors).to be_empty
+      end
+    end
+  end
 end