diff --git a/app/models/derived_variables/lettings_log_variables.rb b/app/models/derived_variables/lettings_log_variables.rb
index 230b2a1dc..ed10b6d72 100644
--- a/app/models/derived_variables/lettings_log_variables.rb
+++ b/app/models/derived_variables/lettings_log_variables.rb
@@ -176,7 +176,7 @@ module DerivedVariables::LettingsLogVariables
 
     if !form.start_year_2026_or_later? && is_supported_housing?
       reset_address_fields!
-    elsif form.start_year_2026_or_later? && location_changed?
+    elsif form.start_year_2026_or_later? && location_changed? && persisted?
       reset_address_fields!
       self.la = nil
     end
diff --git a/spec/features/form/check_answers_page_lettings_logs_spec.rb b/spec/features/form/check_answers_page_lettings_logs_spec.rb
index 62f9fad52..3b6bc69a3 100644
--- a/spec/features/form/check_answers_page_lettings_logs_spec.rb
+++ b/spec/features/form/check_answers_page_lettings_logs_spec.rb
@@ -18,6 +18,7 @@ RSpec.describe "Lettings Log Check Answers Page" do
       needstype: 2,
       scheme:,
       location:,
+      postcode_full: location.postcode,
     )
   end
   let(:empty_lettings_log) do
diff --git a/spec/models/lettings_log_derived_fields_spec.rb b/spec/models/lettings_log_derived_fields_spec.rb
index c418c13cf..e15f6980e 100644
--- a/spec/models/lettings_log_derived_fields_spec.rb
+++ b/spec/models/lettings_log_derived_fields_spec.rb
@@ -1583,6 +1583,39 @@ RSpec.describe LettingsLog, type: :model do
         end
       end
     end
+
+    context "when it is 2026 and the log is new, with a location assigned for the first time (e.g. bulk upload)", metadata: { year: 26 } do
+      let(:startdate) { collection_start_date_for_year(2026) }
+      let(:location_a) { create(:location) }
+      let(:log) { build(:lettings_log, startdate:, assigned_to: user) }
+      let(:la) { "E09000003" }
+
+      around do |example|
+        Timecop.freeze(collection_start_date_for_year(2026)) do
+          Singleton.__init__(FormHandler)
+          example.run
+        end
+      end
+
+      before do
+        allow(location_a).to receive(:lookup_postcode!).and_return(nil)
+
+        log.assign_attributes(location: location_a, uprn:, uprn_known:, uprn_confirmed:, address_line1:, address_line2:, town_or_city:, county:, postcode_full:, la:, manual_address_entry_selected:)
+      end
+
+      it "does not reset the address fields" do
+        expect { log.set_derived_fields! }
+          .to not_change { log.read_attribute(:uprn) }
+          .and not_change { log.read_attribute(:uprn_known) }
+          .and not_change { log.read_attribute(:uprn_confirmed) }
+          .and not_change { log.read_attribute(:address_line1) }
+          .and not_change { log.read_attribute(:address_line2) }
+          .and not_change { log.read_attribute(:town_or_city) }
+          .and not_change { log.read_attribute(:county) }
+          .and(not_change { log.read_attribute(:postcode_full) })
+          .and(not_change { log.read_attribute(:la) })
+      end
+    end
   end
 
   describe "address field behaviour for confidential schemes", metadata: { year: 26 } do
diff --git a/spec/models/lettings_log_spec.rb b/spec/models/lettings_log_spec.rb
index 779b7be4a..166011ecb 100644
--- a/spec/models/lettings_log_spec.rb
+++ b/spec/models/lettings_log_spec.rb
@@ -1965,8 +1965,8 @@ RSpec.describe LettingsLog do
       context "when there is a duplicate supported housing log" do
         let(:scheme) { create(:scheme, owning_organisation: organisation) }
         let(:location) { create(:location, scheme:) }
-        let!(:supported_housing_log) { create(:lettings_log, :duplicate, needstype: 2, location:, scheme:, owning_organisation: organisation) }
-        let!(:duplicate_supported_housing_log) { create(:lettings_log, :duplicate, needstype: 2, location:, scheme:, owning_organisation: organisation) }
+        let!(:supported_housing_log) { create(:lettings_log, :duplicate, needstype: 2, location:, scheme:, owning_organisation: organisation, postcode_full: location.postcode) }
+        let!(:duplicate_supported_housing_log) { create(:lettings_log, :duplicate, needstype: 2, location:, scheme:, owning_organisation: organisation, postcode_full: location.postcode) }
 
         it "returns the log as a duplicate" do
           expect(duplicate_sets).to contain_exactly(