diff --git a/app/models/case_log.rb b/app/models/case_log.rb
index 274a6da52..2426ecc0e 100644
--- a/app/models/case_log.rb
+++ b/app/models/case_log.rb
@@ -180,6 +180,10 @@ class CaseLog < ApplicationRecord
     ALLOWED_INCOME_RANGES[ecstat1.to_sym]
   end
 
+  def first_time_property_let_as_social_housing?
+    first_time_property_let_as_social_housing == "Yes"
+  end
+
 private
 
   PIO = Postcodes::IO.new
diff --git a/app/models/validations/property_validations.rb b/app/models/validations/property_validations.rb
index d520b6dae..828bceb81 100644
--- a/app/models/validations/property_validations.rb
+++ b/app/models/validations/property_validations.rb
@@ -2,6 +2,7 @@ module Validations::PropertyValidations
   # Validations methods need to be called 'validate_<page_name>' to run on model save
   # or 'validate_' to run on submit as well
   include Constants::CaseLog
+
   def validate_property_number_of_times_relet(record)
     if record.offered && !/^[1-9]$|^0[1-9]$|^1[0-9]$|^20$/.match?(record.offered.to_s)
       record.errors.add :offered, "Property number of times relet must be between 0 and 20"
@@ -14,9 +15,22 @@ module Validations::PropertyValidations
     end
   end
 
+  FIRST_LET_VACANCY_REASONS = ["First let of newbuild property",
+                               "First let of conversion/rehabilitation/acquired property",
+                               "First let of leased property"].freeze
+  def validate_rsnvac(record)
+    if !record.first_time_property_let_as_social_housing? && FIRST_LET_VACANCY_REASONS.include?(record.rsnvac)
+      record.errors.add :rsnvac, "Reason for vacancy cannot be first let if unit has been previously let as social housing"
+    end
+
+    if record.first_time_property_let_as_social_housing? && record.rsnvac.present? && !FIRST_LET_VACANCY_REASONS.include?(record.rsnvac)
+      record.errors.add :rsnvac, "Reason for vacancy must be first let if unit has been previously let as social housing"
+    end
+  end
+
   def validate_unitletas(record)
-    if record.unitletas.present? && (record.rsnvac == "First let of newbuild property" || record.rsnvac == "First let of conversion/rehabilitation/acquired property" || record.rsnvac == "First let of leased property")
-      record.errors.add :unitletas, "Can not be completed if it is the first let of the property"
+    if record.first_time_property_let_as_social_housing? && record.unitletas.present?
+      record.errors.add :unitletas, "Property cannot have a previous let type if it is being let as social housing for the first time"
     end
   end
 end
diff --git a/spec/features/form/validations_spec.rb b/spec/features/form/validations_spec.rb
index 4a78c4cf5..4aa72e261 100644
--- a/spec/features/form/validations_spec.rb
+++ b/spec/features/form/validations_spec.rb
@@ -162,19 +162,4 @@ RSpec.describe "validations" do
       end
     end
   end
-
-  describe "Property Validations" do
-    context "first let of property and reason for vacancy completed" do
-      let(:rsnvac) { "First let of newbuild property" }
-      let(:rsnvac1) { "First let of conversion/rehabilitation/acquired property" }
-      let(:rsnvac2) { "First let of leased property" }
-      let(:unitletas) { "Social rent basis" }
-
-      it "throws a validation error", js: true do
-        expect { case_log.update!(rsnvac: rsnvac, unitletas: unitletas) }.to raise_error(ActiveRecord::RecordInvalid)
-        expect { case_log.update!(rsnvac: rsnvac1, unitletas: unitletas) }.to raise_error(ActiveRecord::RecordInvalid)
-        expect { case_log.update!(rsnvac: rsnvac2, unitletas: unitletas) }.to raise_error(ActiveRecord::RecordInvalid)
-      end
-    end
-  end
 end
diff --git a/spec/fixtures/complete_case_log.json b/spec/fixtures/complete_case_log.json
index c7cc65314..4298aad27 100644
--- a/spec/fixtures/complete_case_log.json
+++ b/spec/fixtures/complete_case_log.json
@@ -139,7 +139,7 @@
     "ppostc1": "w3",
     "ppostc2": "w3",
     "why_dont_you_know_la": "Forgot",
-    "first_time_property_let_as_social_housing": "Yes",
+    "first_time_property_let_as_social_housing": "No",
     "unitletas": "Affordable rent basis",
     "builtype": "Purpose built",
     "property_wheelchair_accessible": "Yes",
diff --git a/spec/models/case_log_spec.rb b/spec/models/case_log_spec.rb
index ae3d82b80..90056cc98 100644
--- a/spec/models/case_log_spec.rb
+++ b/spec/models/case_log_spec.rb
@@ -253,6 +253,86 @@ RSpec.describe Form, type: :model do
       end
     end
 
+    context "Property vacancy and let as validations" do
+      it "cannot have a previously let as type, if it hasn't been let before" do
+        expect {
+          CaseLog.create!(
+            first_time_property_let_as_social_housing: "No",
+            unitletas: "Social rent basis",
+            owning_organisation: owning_organisation,
+            managing_organisation: managing_organisation,
+          )
+        }.not_to raise_error
+        expect {
+          CaseLog.create!(
+            first_time_property_let_as_social_housing: "Yes",
+            unitletas: "Social rent basis",
+            owning_organisation: owning_organisation,
+            managing_organisation: managing_organisation,
+          )
+        }.to raise_error(ActiveRecord::RecordInvalid)
+        expect {
+          CaseLog.create!(
+            first_time_property_let_as_social_housing: "Yes",
+            unitletas: "Affordable rent basis",
+            owning_organisation: owning_organisation,
+            managing_organisation: managing_organisation,
+          )
+        }.to raise_error(ActiveRecord::RecordInvalid)
+        expect {
+          CaseLog.create!(
+            first_time_property_let_as_social_housing: "Yes",
+            unitletas: "Intermediate rent basis",
+            owning_organisation: owning_organisation,
+            managing_organisation: managing_organisation,
+          )
+        }.to raise_error(ActiveRecord::RecordInvalid)
+        expect {
+          CaseLog.create!(
+            first_time_property_let_as_social_housing: "Yes",
+            unitletas: "Do not know",
+            owning_organisation: owning_organisation,
+            managing_organisation: managing_organisation,
+          )
+        }.to raise_error(ActiveRecord::RecordInvalid)
+      end
+
+      it "must have a first let reason for vacancy if it's being let as social housing for the first time" do
+        expect {
+          CaseLog.create!(
+            first_time_property_let_as_social_housing: "Yes",
+            rsnvac: "First let of newbuild property",
+            owning_organisation: owning_organisation,
+            managing_organisation: managing_organisation,
+          )
+        }.not_to raise_error
+        expect {
+          CaseLog.create!(
+            first_time_property_let_as_social_housing: "Yes",
+            rsnvac: "First let of conversion/rehabilitation/acquired property",
+            owning_organisation: owning_organisation,
+            managing_organisation: managing_organisation,
+          )
+        }.not_to raise_error
+        expect {
+          CaseLog.create!(
+            first_time_property_let_as_social_housing: "Yes",
+            rsnvac: "First let of leased property",
+            owning_organisation: owning_organisation,
+            managing_organisation: managing_organisation,
+          )
+        }.not_to raise_error
+        expect {
+          CaseLog.create!(
+            first_time_property_let_as_social_housing: "Yes",
+            rsnvac: "Tenant moved to care home",
+            owning_organisation: owning_organisation,
+            managing_organisation: managing_organisation,
+          )
+        }.to raise_error(ActiveRecord::RecordInvalid)
+      end
+    end
+
     context "Shared accomodation bedrooms validation" do
       it "you must have more than zero bedrooms" do
         expect {