diff --git a/app/models/form/sales/questions/mortgageused.rb b/app/models/form/sales/questions/mortgageused.rb
index 2d0bc2dde..aac846662 100644
--- a/app/models/form/sales/questions/mortgageused.rb
+++ b/app/models/form/sales/questions/mortgageused.rb
@@ -16,15 +16,15 @@ class Form::Sales::Questions::Mortgageused < ::Form::Question
     "3" => { "value" => "Don’t know" },
   }.freeze
 
-  def displayed_answer_options(_log, _user = nil)
-    {
-      "1" => { "value" => "Yes" },
-      "2" => { "value" => "No" },
-    }
-  end
-
-  def answer_options(_log, _user = null)
-    log.stairowned == 100
+  def displayed_answer_options(log, _user = nil)
+    if log.stairowned == 100 &&
+      ANSWER_OPTIONS
+    else
+      {
+        "1" => { "value" => "Yes" },
+        "2" => { "value" => "No" },
+      }
+    end
   end
 
   def question_number
diff --git a/app/models/validations/sales/soft_validations.rb b/app/models/validations/sales/soft_validations.rb
index 35f463f63..32ffffd81 100644
--- a/app/models/validations/sales/soft_validations.rb
+++ b/app/models/validations/sales/soft_validations.rb
@@ -135,7 +135,7 @@ module Validations::Sales::SoftValidations
   def discounted_ownership_value_invalid?
     return unless saledate && collection_start_year <= 2023
     return unless value && deposit && ownershipsch
-    return unless mortgage || mortgageused == 2
+    return unless mortgage || mortgageused == 2 || mortgageused == 3
     return unless discount || grant || type == 29
 
     mortgage_deposit_and_grant_total != value_with_discount && discounted_ownership_sale?
diff --git a/spec/models/form/sales/questions/mortgageused_spec.rb b/spec/models/form/sales/questions/mortgageused_spec.rb
index 32fdfde72..12f46643b 100644
--- a/spec/models/form/sales/questions/mortgageused_spec.rb
+++ b/spec/models/form/sales/questions/mortgageused_spec.rb
@@ -48,10 +48,24 @@ RSpec.describe Form::Sales::Questions::Mortgageused, type: :model do
     expect(question.hint_text).to be_nil
   end
 
-  it "has the correct displayed_answer_options" do
-    expect(question.displayed_answer_options(log)).to eq({
-      "1" => { "value" => "Yes" },
-      "2" => { "value" => "No" },
-    })
+  context "staircase owned percentage is 100%" do
+    let(:log) { build(:sales_log, stairowned: 100) }
+    it "show's the don't know option" do
+      expect(question.displayed_answer_options(log)).to eq({
+         "1" => { "value" => "Yes" },
+         "2" => { "value" => "No" },
+         "3" => { "value" => "Don’t know" }
+      })
+    end
+  end
+
+  context "staircase owned percentage is less than 100%" do
+    let(:log) { build(:sales_log, stairowned: 99) }
+    it "show's the don't know option" do
+      expect(question.displayed_answer_options(log)).to eq({
+       "1" => { "value" => "Yes" },
+       "2" => { "value" => "No" },
+     })
+    end
   end
 end