diff --git a/app/models/form/sales/pages/mortgage_length.rb b/app/models/form/sales/pages/mortgage_length.rb
index 979369bdd..55b286bd3 100644
--- a/app/models/form/sales/pages/mortgage_length.rb
+++ b/app/models/form/sales/pages/mortgage_length.rb
@@ -8,6 +8,7 @@ class Form::Sales::Pages::MortgageLength < ::Form::Page
 
   def questions
     @questions ||= [
+      Form::Sales::Questions::MortgageLengthKnown.new(nil, nil, self),
       Form::Sales::Questions::MortgageLength.new(nil, nil, self),
     ]
   end
diff --git a/app/models/form/sales/questions/mortgage_length.rb b/app/models/form/sales/questions/mortgage_length.rb
index 3f1603b75..45b1ebb25 100644
--- a/app/models/form/sales/questions/mortgage_length.rb
+++ b/app/models/form/sales/questions/mortgage_length.rb
@@ -10,5 +10,9 @@ class Form::Sales::Questions::MortgageLength < ::Form::Question
     @width = 5
     @suffix = " years"
     @hint_text = "You should round up to the nearest year. Value should not exceed 60 years."
+    @inferred_check_answers_value = [{
+      "condition" => { "mortlen_known" => 1 },
+      "value" => "Not known",
+    }]
   end
 end
diff --git a/app/models/form/sales/questions/mortgage_length_known.rb b/app/models/form/sales/questions/mortgage_length_known.rb
new file mode 100644
index 000000000..3455d17a8
--- /dev/null
+++ b/app/models/form/sales/questions/mortgage_length_known.rb
@@ -0,0 +1,28 @@
+class Form::Sales::Questions::MortgageLengthKnown < ::Form::Question
+  def initialize(id, hsh, page)
+    super
+    @id = "mortlen_known"
+    @check_answer_label = "Mortgage length known"
+    @header = "Do you know the mortgage length?"
+    @type = "radio"
+    @answer_options = ANSWER_OPTIONS
+    @conditional_for = {
+      "mortlen" => [0],
+    }
+    @hidden_in_check_answers = {
+      "depends_on" => [
+        {
+          "mortlen_known" => 0,
+        },
+        {
+          "mortlen_known" => 1,
+        },
+      ],
+    }
+  end
+
+  ANSWER_OPTIONS = {
+    "0" => { "value" => "Yes" },
+    "1" => { "value" => "No" },
+  }.freeze
+end
diff --git a/app/services/imports/sales_logs_import_service.rb b/app/services/imports/sales_logs_import_service.rb
index deea3fab6..440ae5f71 100644
--- a/app/services/imports/sales_logs_import_service.rb
+++ b/app/services/imports/sales_logs_import_service.rb
@@ -118,6 +118,7 @@ module Imports
       attributes["mortgagelender"] = mortgage_lender(xml_doc, attributes)
       attributes["mortgagelenderother"] = mortgage_lender_other(xml_doc, attributes)
       attributes["mortlen"] = mortgage_length(xml_doc, attributes)
+      attributes["mortlen_known"] = 0 if attributes["mortlen"].present?
       attributes["extrabor"] = borrowing(xml_doc, attributes)
       attributes["totadult"] = safe_string_as_integer(xml_doc, "TOTADULT") # would get overridden
       attributes["totchild"] = safe_string_as_integer(xml_doc, "TOTCHILD") # would get overridden
@@ -404,6 +405,7 @@ module Imports
       attributes["hb"] ||= 4
       attributes["prevown"] ||= 3
       attributes["savingsnk"] ||= attributes["savings"].present? ? 0 : 1
+      attributes["mortlen_known"] ||= 1 if attributes["mortgage"].blank?
       # attributes["noint"] = 1 # not interviewed
 
       # buyer 1 characteristics
diff --git a/db/migrate/20230228112317_add_mortgage_length_known.rb b/db/migrate/20230228112317_add_mortgage_length_known.rb
new file mode 100644
index 000000000..7d2d8a0b2
--- /dev/null
+++ b/db/migrate/20230228112317_add_mortgage_length_known.rb
@@ -0,0 +1,5 @@
+class AddMortgageLengthKnown < ActiveRecord::Migration[7.0]
+  def change
+    add_column :sales_logs, :mortlen_known, :integer
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index d1668b738..be59aaf92 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.0].define(version: 2023_02_15_112932) do
+ActiveRecord::Schema[7.0].define(version: 2023_02_28_112317) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
 
@@ -490,7 +490,6 @@ ActiveRecord::Schema[7.0].define(version: 2023_02_15_112932) do
     t.integer "prevten"
     t.integer "mortgageused"
     t.integer "wchair"
-    t.integer "income2_value_check"
     t.integer "armedforcesspouse"
     t.datetime "hodate", precision: nil
     t.integer "hoday"
@@ -527,10 +526,12 @@ ActiveRecord::Schema[7.0].define(version: 2023_02_15_112932) do
     t.integer "details_known_6"
     t.integer "ethnic_group2"
     t.integer "ethnicbuy2"
-    t.integer "proplen_asked"
     t.integer "prevshared"
     t.integer "staircasesale"
     t.string "old_id"
+    t.integer "income2_value_check"
+    t.integer "proplen_asked"
+    t.integer "mortlen_known"
     t.index ["bulk_upload_id"], name: "index_sales_logs_on_bulk_upload_id"
     t.index ["created_by_id"], name: "index_sales_logs_on_created_by_id"
     t.index ["old_id"], name: "index_sales_logs_on_old_id", unique: true
diff --git a/spec/factories/sales_log.rb b/spec/factories/sales_log.rb
index f1da841a4..d2294dbd9 100644
--- a/spec/factories/sales_log.rb
+++ b/spec/factories/sales_log.rb
@@ -95,6 +95,7 @@ FactoryBot.define do
       armedforcesspouse { 5 }
       mscharge_known { 1 }
       mscharge { 100 }
+      mortlen_known { 0 }
       mortlen { 10 }
       pcodenk { 1 }
       is_la_inferred { false }
diff --git a/spec/models/form/sales/pages/mortgage_length_spec.rb b/spec/models/form/sales/pages/mortgage_length_spec.rb
index ef2573e57..394ec94ab 100644
--- a/spec/models/form/sales/pages/mortgage_length_spec.rb
+++ b/spec/models/form/sales/pages/mortgage_length_spec.rb
@@ -12,7 +12,7 @@ RSpec.describe Form::Sales::Pages::MortgageLength, type: :model do
   end
 
   it "has correct questions" do
-    expect(page.questions.map(&:id)).to eq(%w[mortlen])
+    expect(page.questions.map(&:id)).to eq(%w[mortlen_known mortlen])
   end
 
   it "has the correct id" do
diff --git a/spec/models/form/sales/questions/mortgage_length_known_spec.rb b/spec/models/form/sales/questions/mortgage_length_known_spec.rb
new file mode 100644
index 000000000..b58a142d5
--- /dev/null
+++ b/spec/models/form/sales/questions/mortgage_length_known_spec.rb
@@ -0,0 +1,55 @@
+require "rails_helper"
+
+RSpec.describe Form::Sales::Questions::MortgageLengthKnown, type: :model do
+  subject(:question) { described_class.new(question_id, question_definition, page) }
+
+  let(:question_id) { nil }
+  let(:question_definition) { nil }
+  let(:page) { instance_double(Form::Page) }
+
+  it "has correct page" do
+    expect(question.page).to eq(page)
+  end
+
+  it "has the correct id" do
+    expect(question.id).to eq("mortlen_known")
+  end
+
+  it "has the correct header" do
+    expect(question.header).to eq("Do you know the mortgage length?")
+  end
+
+  it "has the correct check_answer_label" do
+    expect(question.check_answer_label).to eq("Mortgage length known")
+  end
+
+  it "has the correct type" do
+    expect(question.type).to eq("radio")
+  end
+
+  it "is not marked as derived" do
+    expect(question.derived?).to be false
+  end
+
+  it "has the correct answer_options" do
+    expect(question.answer_options).to eq({
+      "0" => { "value" => "Yes" },
+      "1" => { "value" => "No" },
+    })
+  end
+
+  it "has correct conditional for" do
+    expect(question.conditional_for).to eq({
+      "mortlen" => [0],
+    })
+  end
+
+  it "has correct hidden in check answers" do
+    expect(question.hidden_in_check_answers).to eq({
+      "depends_on" => [{
+        "mortlen_known" => 0,
+      },
+                       { "mortlen_known" => 1 }],
+    })
+  end
+end
diff --git a/spec/models/form/sales/questions/mortgage_length_spec.rb b/spec/models/form/sales/questions/mortgage_length_spec.rb
index 0f3193244..75db84658 100644
--- a/spec/models/form/sales/questions/mortgage_length_spec.rb
+++ b/spec/models/form/sales/questions/mortgage_length_spec.rb
@@ -52,4 +52,13 @@ RSpec.describe Form::Sales::Questions::MortgageLength, type: :model do
   it "has correct max" do
     expect(question.max).to eq(60)
   end
+
+  it "has correct inferred check answers value" do
+    expect(question.inferred_check_answers_value).to eq([
+      {
+        "condition" => { "mortlen_known" => 1 },
+        "value" => "Not known",
+      },
+    ])
+  end
 end