diff --git a/app/models/case_log.rb b/app/models/case_log.rb
index 1f4219d57..9a84c633e 100644
--- a/app/models/case_log.rb
+++ b/app/models/case_log.rb
@@ -97,6 +97,14 @@ private
   end
 
   def mandatory_fields
-    attributes.except(*AUTOGENERATED_FIELDS)
+    required = attributes.except(*AUTOGENERATED_FIELDS)
+
+    dynamically_not_required = []
+
+    if reason_for_leaving_last_settled_home != "Other"
+      dynamically_not_required << "other_reason_for_leaving_last_settled_home"
+    end
+
+    required.delete_if { |key, _value| dynamically_not_required.include?(key) }
   end
 end
diff --git a/spec/fixtures/complete_case_log.json b/spec/fixtures/complete_case_log.json
index 11f073714..da2e0da20 100644
--- a/spec/fixtures/complete_case_log.json
+++ b/spec/fixtures/complete_case_log.json
@@ -89,7 +89,7 @@
       "chr_letting": false,
       "cap_letting": false,
       "outstanding_rent_or_charges": 25,
-      "other_reason_for_leaving_last_settled_home": "Other reason",
+      "other_reason_for_leaving_last_settled_home": null,
       "accessibility_requirements_fully_wheelchair_accessible_housing": true,
       "accessibility_requirements_wheelchair_access_to_essential_rooms": false,
       "accessibility_requirements_level_access_housing": false,