diff --git a/app/models/form.rb b/app/models/form.rb
index 80fed4444..4eb57fd1c 100644
--- a/app/models/form.rb
+++ b/app/models/form.rb
@@ -230,6 +230,21 @@ class Form
     questions.select { |q| q.type == "numeric" }
   end
 
+  def radio_questions_valid_options
+    questions.select { |q| q.type == "radio" }
+             .group_by(:id)
+             .transform_values! do |q_array|
+               q_array.flat_map { |q| q.answer_options.keys }
+             end
+  end
+
+  def previous_page(page_ids, page_index, log, current_user)
+    prev_page = get_page(page_ids[page_index - 1])
+    return prev_page.id if prev_page.routed_to?(log, current_user)
+
+    previous_page(page_ids, page_index - 1, log, current_user)
+  end
+
   def send_chain(arr, log)
     Array(arr).inject(log) { |o, a| o.public_send(*a) }
   end
diff --git a/app/models/lettings_log.rb b/app/models/lettings_log.rb
index cd1fffd22..daab8a34e 100644
--- a/app/models/lettings_log.rb
+++ b/app/models/lettings_log.rb
@@ -26,6 +26,7 @@ class LettingsLog < Log
 
   validates_with LettingsLogValidator
   before_validation :recalculate_start_year!, if: :startdate_changed?
+  before_validation :clear_invalid_radio_answers!, if: :startdate_changed?
   before_validation :reset_scheme_location!, if: :scheme_changed?, unless: :location_changed?
   before_validation :process_postcode_changes!, if: :postcode_full_changed?
   before_validation :process_previous_postcode_changes!, if: :ppostcode_full_changed?
@@ -80,6 +81,10 @@ class LettingsLog < Log
     FormHandler.instance.form_name_from_start_year(collection_start_year, "lettings")
   end
 
+  def clear_invalid_radio_answers!
+    super if startdate_was && @start_year != FormHandler.instance.collection_start_year(startdate_was)
+  end
+
   def self.editable_fields
     attribute_names - AUTOGENERATED_FIELDS
   end
diff --git a/app/models/log.rb b/app/models/log.rb
index 33d3c4547..5da5c037b 100644
--- a/app/models/log.rb
+++ b/app/models/log.rb
@@ -63,6 +63,14 @@ class Log < ApplicationRecord
     end
   end
 
+  def clear_invalid_radio_answers!
+    form.radio_questions_valid_options.each do |question_id, valid_options|
+      next unless (value = self[question_id])
+
+      self[question_id] = nil unless valid_options.include?(value.to_s)
+    end
+  end
+
   def collection_start_year
     return @start_year if @start_year
 
diff --git a/app/models/sales_log.rb b/app/models/sales_log.rb
index ebb3ef4e3..c1fc7fbae 100644
--- a/app/models/sales_log.rb
+++ b/app/models/sales_log.rb
@@ -26,6 +26,7 @@ class SalesLog < Log
 
   validates_with SalesLogValidator
   before_validation :recalculate_start_year!, if: :saledate_changed?
+  before_validation :clear_invalid_radio_answers!, if: :saledate_changed?
   before_validation :reset_invalidated_dependent_fields!
   before_validation :process_postcode_changes!, if: :postcode_full_changed?
   before_validation :process_previous_postcode_changes!, if: :ppostcode_full_changed?
@@ -76,6 +77,10 @@ class SalesLog < Log
     OPTIONAL_FIELDS + dynamically_not_required
   end
 
+  def clear_invalid_radio_answers!
+    super if saledate_was && @start_year != FormHandler.instance.collection_start_year(saledate_was)
+  end
+
   def dynamically_not_required
     not_required = []
     not_required << "proplen" if proplen_optional?