diff --git a/spec/factories/lettings_log.rb b/spec/factories/lettings_log.rb
index ef681bd6b..58c81e8f3 100644
--- a/spec/factories/lettings_log.rb
+++ b/spec/factories/lettings_log.rb
@@ -161,6 +161,9 @@ FactoryBot.define do
     trait :sheltered_housing do
       needstype { 2 }
     end
+    trait :startdate_today do
+      startdate { Time.zone.today }
+    end
     created_at { Time.zone.today }
     updated_at { Time.zone.today }
   end
diff --git a/spec/factories/sales_log.rb b/spec/factories/sales_log.rb
index 104694d2a..3cf011fd5 100644
--- a/spec/factories/sales_log.rb
+++ b/spec/factories/sales_log.rb
@@ -12,6 +12,27 @@ FactoryBot.define do
     end
     trait :shared_ownership do
       ownershipsch { 1 }
+      type { 30 }
+    end
+    trait :privacy_notice_seen do
+      privacynotice { 1 }
+    end
+    trait :saledate_today do
+      saledate { Time.zone.today }
+    end
+    trait :shared_ownership_setup_complete do
+      saledate { Time.zone.today }
+      ownershipsch { 1 }
+      type { 30 }
+      jointpur { 2 }
+    end
+    trait :outright_sale_setup_complete do
+      saledate { Time.zone.today }
+      ownershipsch { 3 }
+      type { 10 }
+      companybuy { 2 }
+      buylivein { 1 }
+      jointpur { 2 }
     end
     trait :completed do
       ownershipsch { 2 }
diff --git a/spec/models/form_spec.rb b/spec/models/form_spec.rb
index f2a80efe3..957ff0f1a 100644
--- a/spec/models/form_spec.rb
+++ b/spec/models/form_spec.rb
@@ -204,32 +204,140 @@ RSpec.describe Form, type: :model do
     end
   end
 
-  describe "invalidated_page_questions" do
-    let(:lettings_log) { FactoryBot.create(:lettings_log, :in_progress, needstype: 1) }
-    let(:expected_invalid) { %w[scheme_id retirement_value_check condition_effects cbl conditional_question_no_second_question net_income_value_check dependent_question offered layear declaration] }
+  describe "#reset_not_routed_questions_and_invalid_answers" do
+    around do |example|
+      Singleton.__init__(FormHandler)
+      Timecop.freeze(now) do
+        FormHandler.instance.use_real_forms!
+        example.run
+      end
+      FormHandler.instance.use_fake_forms!
+    end
+
+    let(:now) { Time.zone.local(2023, 5, 5) }
+
+    context "when there are multiple radio questions for attribute X" do
+      context "and attribute Y is changed such that a different question for X is routed to" do
+        let(:log) { FactoryBot.create(:lettings_log, :about_completed, :sheltered_housing, startdate: now, renewal: 0, prevten:) }
+
+        context "and the value of X remains valid" do
+          let(:prevten) { 36 }
 
-    context "when dependencies are not met" do
-      it "returns an array of question keys whose pages conditions are not met" do
-        expect(form.invalidated_page_questions(lettings_log).map(&:id).uniq).to eq(expected_invalid)
+          it "the value of this attribute is not cleared" do
+            log.renewal = 1
+            log.form.reset_not_routed_questions_and_invalid_answers(log)
+            expect(log.prevten).to be 36
+          end
+        end
+
+        context "and the value of X is now invalid" do
+          let(:prevten) { 30 }
+
+          it "the value of this attribute is cleared" do
+            log.renewal = 1
+            log.form.reset_not_routed_questions_and_invalid_answers(log)
+            expect(log.prevten).to be nil
+          end
+        end
       end
     end
 
-    context "with two pages having the same question and only one has dependencies met" do
-      it "returns an array of question keys whose pages conditions are not met" do
-        lettings_log["preg_occ"] = "No"
-        expect(form.invalidated_page_questions(lettings_log).map(&:id).uniq).to eq(expected_invalid)
+    context "when there is one radio question for attribute X" do
+      context "and the start date or sale date is changed such that the collection year changes and there are different options" do
+        let(:log) { FactoryBot.create(:lettings_log, :about_completed, :sheltered_housing, startdate: now, sheltered:) }
+
+        context "and the value of X remains valid" do
+          let(:sheltered) { 2 }
+
+          it "the value of this attribute is not cleared" do
+            log.update!(startdate: Time.zone.local(2023, 1, 1))
+            expect(log.sheltered).to be 2
+          end
+        end
+
+        context "and the value of X is now invalid" do
+          let(:sheltered) { 5 }
+
+          it "the value of this attribute is cleared" do
+            log.update!(startdate: Time.zone.local(2023, 1, 1))
+            expect(log.sheltered).to be nil
+          end
+        end
       end
     end
 
-    context "when a question is marked as `derived` and `depends_on: false`" do
-      let(:lettings_log) { FactoryBot.build(:lettings_log, :in_progress, startdate: Time.utc(2022, 4, 2, 10, 36, 49)) }
+    context "when there is one free user input question for an attribute X" do
+      let(:log) { FactoryBot.create(:sales_log, :shared_ownership_setup_complete, staircase: 1, stairbought: 25) }
 
-      it "does not count it's questions as invalidated" do
-        expect(form.enabled_page_questions(lettings_log).map(&:id).uniq).to include("tshortfall_known")
+      context "and attribute Y is changed such that it is no longer routed to" do
+        it "the value of this attribute is cleared" do
+          expect(log.stairbought).to be 25
+          log.staircase = 2
+          log.form.reset_not_routed_questions_and_invalid_answers(log)
+          expect(log.stairbought).to be nil
+        end
       end
+    end
+
+    context "when there are multiple free user input questions for attribute X" do
+      context "and attribute Y is changed such that a different question for X is routed to" do
+        let(:log) { FactoryBot.create(:sales_log, :saledate_today, :shared_ownership, :privacy_notice_seen, jointpur: 1, jointmore: 2, hholdcount: expected_hholdcount) }
+        let(:expected_hholdcount) { 2 }
+
+        it "the value of this attribute is not cleared" do
+          log.jointpur = 2
+          log.form.reset_not_routed_questions_and_invalid_answers(log)
+          expect(log.hholdcount).to eq expected_hholdcount
+        end
+      end
+
+      context "and attribute Y is changed such that no questions for X are routed to" do
+        let(:log) { FactoryBot.create(:sales_log, :shared_ownership_setup_complete, value: initial_value) }
+        let(:initial_value) { 200_000.to_d }
+
+        it "the value of this attribute is cleared" do
+          expect(log.value).to eq initial_value
+          log.ownershipsch = 2
+          log.form.reset_not_routed_questions_and_invalid_answers(log)
+          expect(log.value).to be nil
+        end
+      end
+    end
+
+    context "when a value is changed such that a checkbox question is no longer routed to" do
+      let(:log) { FactoryBot.create(:lettings_log, :about_completed, startdate: now, reasonpref: 1, rp_homeless: 1, rp_medwel: 1, rp_hardship: 1) }
+
+      it "all attributes relating to that checkbox question are cleared" do
+        expect(log.rp_homeless).to be 1
+        log.reasonpref = 2
+        log.form.reset_not_routed_questions_and_invalid_answers(log)
+        expect(log.rp_homeless).to be nil
+        expect(log.rp_medwel).to be nil
+        expect(log.rp_hardship).to be nil
+      end
+    end
+
+    context "when an attribute is derived, but no questions for that attribute are routed to" do
+      let(:log) { FactoryBot.create(:sales_log, :outright_sale_setup_complete, value: 200_000) }
+
+      it "the value of this attribute is not cleared" do
+        expect(log.deposit).to be nil
+        log.update!(mortgageused: 2)
+        expect(log.form.questions.any? { |q| q.id == "deposit" && q.page.routed_to?(log, nil) }).to be false
+        expect(log.deposit).not_to be nil
+      end
+    end
+
+    context "when an attribute is related to a callback question with no set answer options, and no questions for that attribute are routed to" do
+      let(:location) { FactoryBot.create(:location) }
+      let(:log) { FactoryBot.create(:lettings_log, :startdate_today) }
 
-      it "does not route to the page" do
-        expect(form.invalidated_pages(lettings_log).map(&:id)).to include("outstanding_amount_known")
+      # Pages::PropertyPostcode and questions inside have been removed from form. do we not want to delete and migration delete_column?
+      it "the value of this attribute is not cleared" do
+        expect(log.form.questions.find { |q| q.id == "location_id" }.answer_options.keys).to be_empty
+        log.location_id = location.id
+        log.form.reset_not_routed_questions_and_invalid_answers(log)
+        expect(log.location_id).not_to be nil
       end
     end
   end