diff --git a/app/models/case_log.rb b/app/models/case_log.rb
index 5905be31c..6397a0e6b 100644
--- a/app/models/case_log.rb
+++ b/app/models/case_log.rb
@@ -123,6 +123,10 @@ class CaseLog < ApplicationRecord
     needstype == 1
   end
 
+  def is_supported_housing?
+    !!(needstype && needstype.zero?)
+  end
+
   def has_hbrentshortfall?
     !!(hbrentshortfall && hbrentshortfall.zero?)
   end
@@ -378,24 +382,21 @@ private
 
     case RENT_TYPE_MAPPING_LABELS[renttype]
     when "Social Rent"
-      case needstype
-      when 0
+      if is_supported_housing?
         owning_organisation[:provider_type] == "PRP" ? 2 : 4
-      when 1
+      elsif is_general_needs?
         owning_organisation[:provider_type] == "PRP" ? 1 : 3
       end
     when "Affordable Rent"
-      case needstype
-      when 0
+      if is_supported_housing?
         owning_organisation[:provider_type] == "PRP" ? 6 : 8
-      when 1
+      elsif is_general_needs?
         owning_organisation[:provider_type] == "PRP" ? 5 : 7
       end
     when "Intermediate Rent"
-      case needstype
-      when 0
+      if is_supported_housing?
         owning_organisation[:provider_type] == "PRP" ? 10 : 12
-      when 1
+      elsif is_general_needs?
         owning_organisation[:provider_type] == "PRP" ? 9 : 11
       end
     end
diff --git a/spec/models/case_log_spec.rb b/spec/models/case_log_spec.rb
index 3c76b3365..ad7b255d7 100644
--- a/spec/models/case_log_spec.rb
+++ b/spec/models/case_log_spec.rb
@@ -273,10 +273,120 @@ RSpec.describe CaseLog do
       expect(record_from_db["renttype"]).to eq(3)
     end
 
-    it "correctly derives and saves lettype" do
-      record_from_db = ActiveRecord::Base.connection.execute("select lettype from case_logs where id=#{case_log.id}").to_a[0]
-      expect(case_log.lettype).to eq(9)
-      expect(record_from_db["lettype"]).to eq(9)
+    context "when deriving lettype" do
+      context "when the owning organisation is a PRP" do
+        context "when the rent type is intermediate rent and supported housing" do
+          it "correctly derives and saves lettype" do
+            case_log.update!(rent_type: 4, needstype: 0)
+            record_from_db = ActiveRecord::Base.connection.execute("select lettype from case_logs where id=#{case_log.id}").to_a[0]
+            expect(case_log.lettype).to eq(10)
+            expect(record_from_db["lettype"]).to eq(10)
+          end
+        end
+
+        context "when the rent type is intermediate rent and general needs housing" do
+          it "correctly derives and saves lettype" do
+            case_log.update!(rent_type: 4, needstype: 1)
+            record_from_db = ActiveRecord::Base.connection.execute("select lettype from case_logs where id=#{case_log.id}").to_a[0]
+            expect(case_log.lettype).to eq(9)
+            expect(record_from_db["lettype"]).to eq(9)
+          end
+        end
+
+        context "when the rent type is affordable rent and supported housing" do
+          it "correctly derives and saves lettype" do
+            case_log.update!(rent_type: 2, needstype: 0)
+            record_from_db = ActiveRecord::Base.connection.execute("select lettype from case_logs where id=#{case_log.id}").to_a[0]
+            expect(case_log.lettype).to eq(6)
+            expect(record_from_db["lettype"]).to eq(6)
+          end
+        end
+
+        context "when the rent type is affordable rent and general needs housing" do
+          it "correctly derives and saves lettype" do
+            case_log.update!(rent_type: 2, needstype: 1)
+            record_from_db = ActiveRecord::Base.connection.execute("select lettype from case_logs where id=#{case_log.id}").to_a[0]
+            expect(case_log.lettype).to eq(5)
+            expect(record_from_db["lettype"]).to eq(5)
+          end
+        end
+
+        context "when the rent type is social rent and supported housing" do
+          it "correctly derives and saves lettype" do
+            case_log.update!(rent_type: 0, needstype: 0)
+            record_from_db = ActiveRecord::Base.connection.execute("select lettype from case_logs where id=#{case_log.id}").to_a[0]
+            expect(case_log.lettype).to eq(2)
+            expect(record_from_db["lettype"]).to eq(2)
+          end
+        end
+
+        context "when the rent type is social rent and general needs housing" do
+          it "correctly derives and saves lettype" do
+            case_log.update!(rent_type: 0, needstype: 1)
+            record_from_db = ActiveRecord::Base.connection.execute("select lettype from case_logs where id=#{case_log.id}").to_a[0]
+            expect(case_log.lettype).to eq(1)
+            expect(record_from_db["lettype"]).to eq(1)
+          end
+        end
+      end
+
+      context "when the owning organisation is an LA" do
+        let(:organisation) { FactoryBot.create(:organisation, provider_type: "LA") }
+
+        context "when the rent type is intermediate rent and supported housing" do
+          it "correctly derives and saves lettype" do
+            case_log.update!(rent_type: 4, needstype: 0)
+            record_from_db = ActiveRecord::Base.connection.execute("select lettype from case_logs where id=#{case_log.id}").to_a[0]
+            expect(case_log.lettype).to eq(12)
+            expect(record_from_db["lettype"]).to eq(12)
+          end
+        end
+
+        context "when the rent type is intermediate rent and general needs housing" do
+          it "correctly derives and saves lettype" do
+            case_log.update!(rent_type: 4, needstype: 1)
+            record_from_db = ActiveRecord::Base.connection.execute("select lettype from case_logs where id=#{case_log.id}").to_a[0]
+            expect(case_log.lettype).to eq(11)
+            expect(record_from_db["lettype"]).to eq(11)
+          end
+        end
+
+        context "when the rent type is affordable rent and supported housing" do
+          it "correctly derives and saves lettype" do
+            case_log.update!(rent_type: 2, needstype: 0)
+            record_from_db = ActiveRecord::Base.connection.execute("select lettype from case_logs where id=#{case_log.id}").to_a[0]
+            expect(case_log.lettype).to eq(8)
+            expect(record_from_db["lettype"]).to eq(8)
+          end
+        end
+
+        context "when the rent type is affordable rent and general needs housing" do
+          it "correctly derives and saves lettype" do
+            case_log.update!(rent_type: 2, needstype: 1)
+            record_from_db = ActiveRecord::Base.connection.execute("select lettype from case_logs where id=#{case_log.id}").to_a[0]
+            expect(case_log.lettype).to eq(7)
+            expect(record_from_db["lettype"]).to eq(7)
+          end
+        end
+
+        context "when the rent type is social rent and supported housing" do
+          it "correctly derives and saves lettype" do
+            case_log.update!(rent_type: 0, needstype: 0)
+            record_from_db = ActiveRecord::Base.connection.execute("select lettype from case_logs where id=#{case_log.id}").to_a[0]
+            expect(case_log.lettype).to eq(4)
+            expect(record_from_db["lettype"]).to eq(4)
+          end
+        end
+
+        context "when the rent type is social rent and general needs housing" do
+          it "correctly derives and saves lettype" do
+            case_log.update!(rent_type: 0, needstype: 1)
+            record_from_db = ActiveRecord::Base.connection.execute("select lettype from case_logs where id=#{case_log.id}").to_a[0]
+            expect(case_log.lettype).to eq(3)
+            expect(record_from_db["lettype"]).to eq(3)
+          end
+        end
+      end
     end
 
     it "correctly derives and saves day, month, year from start date" do
diff --git a/spec/models/form/question_spec.rb b/spec/models/form/question_spec.rb
index d82293907..83fe9cc88 100644
--- a/spec/models/form/question_spec.rb
+++ b/spec/models/form/question_spec.rb
@@ -238,6 +238,18 @@ RSpec.describe Form::Question, type: :model do
         case_log.hb = "Housing benefit"
         expect(question.enabled?(case_log)).to be true
       end
+
+      context "when the condition type hasn't been implemented yet" do
+        let(:unimplemented_question) { OpenStruct.new(id: "hb", type: "unkown") }
+
+        before do
+          allow(page).to receive(:questions).and_return([unimplemented_question])
+        end
+
+        it "raises an exception" do
+          expect { question.enabled?(case_log) }.to raise_error("Not implemented yet")
+        end
+      end
     end
 
     context "when answers have a suffix dependent on another answer" do