diff --git a/app/models/derived_variables/sales_log_variables.rb b/app/models/derived_variables/sales_log_variables.rb
index 88bad228f..5fff0900d 100644
--- a/app/models/derived_variables/sales_log_variables.rb
+++ b/app/models/derived_variables/sales_log_variables.rb
@@ -6,5 +6,6 @@ module DerivedVariables::SalesLogVariables
       self.exmonth = exdate.month
       self.exyear = exdate.year
     end
+    self.deposit = value if outright_sale? && mortgage_not_used?
   end
 end
diff --git a/app/models/sales_log.rb b/app/models/sales_log.rb
index 86c23e0ce..ccc80ce7a 100644
--- a/app/models/sales_log.rb
+++ b/app/models/sales_log.rb
@@ -143,4 +143,12 @@ class SalesLog < Log
     self[la_inferred_key] = inferred_la.present?
     self[la_key] = inferred_la if inferred_la.present?
   end
+  
+  def outright_sale?
+    ownershipsch == 3
+  end
+
+  def mortgage_not_used?
+    mortgageused == 2
+  end
 end
diff --git a/spec/models/sales_log_spec.rb b/spec/models/sales_log_spec.rb
index 5942b3d84..ebfd7009d 100644
--- a/spec/models/sales_log_spec.rb
+++ b/spec/models/sales_log_spec.rb
@@ -92,18 +92,33 @@ RSpec.describe SalesLog, type: :model do
   end
 
   describe "derived variables" do
-    let!(:sales_log) do
-      described_class.create({
-        exdate: Time.gm(2022, 5, 4),
-      })
-    end
+    let(:sales_log) { FactoryBot.create(:sales_log, :completed) }
 
     it "correctly derives and saves exday, exmonth and exyear" do
+      sales_log.update!(exdate: Time.gm(2022, 5, 4))
       record_from_db = ActiveRecord::Base.connection.execute("select exday, exmonth, exyear from sales_logs where id=#{sales_log.id}").to_a[0]
       expect(record_from_db["exday"]).to eq(4)
       expect(record_from_db["exmonth"]).to eq(5)
       expect(record_from_db["exyear"]).to eq(2022)
     end
+
+    it "correctly derives and saves deposit for outright sales when no mortgage is used" do
+      sales_log.update!(value: 123_400, deposit: nil, mortgageused: 2, ownershipsch: 3, type: 10, companybuy: 1, jointpur: 1, jointmore: 1)
+      record_from_db = ActiveRecord::Base.connection.execute("select deposit from sales_logs where id=#{sales_log.id}").to_a[0]
+      expect(record_from_db["deposit"]).to eq(123_400)
+    end
+
+    it "does not derive deposit if the sale isn't outright" do
+      sales_log.update!(value: 123_400, deposit: nil, mortgageused: 2, ownershipsch: 2)
+      record_from_db = ActiveRecord::Base.connection.execute("select deposit from sales_logs where id=#{sales_log.id}").to_a[0]
+      expect(record_from_db["deposit"]).to eq(nil)
+    end
+
+    it "does not derive deposit if the mortgage is used" do
+      sales_log.update!(value: 123_400, deposit: nil, mortgageused: 1, ownershipsch: 3, type: 10, companybuy: 1, jointpur: 1, jointmore: 1)
+      record_from_db = ActiveRecord::Base.connection.execute("select deposit from sales_logs where id=#{sales_log.id}").to_a[0]
+      expect(record_from_db["deposit"]).to eq(nil)
+    end
   end
 
   context "when saving previous address" do