diff --git a/app/services/imports/lettings_logs_field_import_service.rb b/app/services/imports/lettings_logs_field_import_service.rb
index 3c6bccf87..26785af03 100644
--- a/app/services/imports/lettings_logs_field_import_service.rb
+++ b/app/services/imports/lettings_logs_field_import_service.rb
@@ -28,6 +28,8 @@ module Imports
         import_from(folder, :update_person_details)
       when "childrens_care_referral"
         import_from(folder, :update_childrens_care_referral)
+      when "old_form_id"
+        import_from(folder, :update_old_form_id)
       else
         raise "Updating #{field} is not supported by the field import service"
       end
@@ -432,5 +434,24 @@ module Imports
       record.update!(referral: 17, values_updated_at: Time.zone.now)
       @logger.info("lettings log #{record.id}'s referral value has been set to 17")
     end
+
+    def update_old_form_id(xml_doc)
+      return if meta_field_value(xml_doc, "form-name").include?("Sales")
+
+      old_id = meta_field_value(xml_doc, "document-id")
+      record = LettingsLog.find_by(old_id:)
+
+      if record.present?
+        if record.old_form_id.present?
+          @logger.info("lettings log #{record.id} has a value for old_form_id, skipping update")
+        else
+          old_form_id = safe_string_as_integer(xml_doc, "FORM")
+          record.update!(old_form_id:)
+          @logger.info("lettings log #{record.id}'s old_form_id value has been set to #{old_form_id}")
+        end
+      else
+        @logger.warn("lettings log with old id #{old_id} not found")
+      end
+    end
   end
 end
diff --git a/lib/tasks/data_import_field.rake b/lib/tasks/data_import_field.rake
index e2f709929..dc7f18a13 100644
--- a/lib/tasks/data_import_field.rake
+++ b/lib/tasks/data_import_field.rake
@@ -7,7 +7,7 @@ namespace :core do
 
     # We only allow a reduced list of known fields to be updatable
     case field
-    when "tenancycode", "major_repairs", "lettings_allocation", "offered", "address", "reason", "homeless", "created_by", "sex_and_relat", "general_needs_referral", "person_details", "childrens_care_referral"
+    when "tenancycode", "major_repairs", "lettings_allocation", "offered", "address", "reason", "homeless", "created_by", "sex_and_relat", "general_needs_referral", "person_details", "childrens_care_referral", "old_form_id"
       s3_service = Storage::S3Service.new(PlatformHelper.is_paas? ? Configuration::PaasConfigurationService.new : Configuration::EnvConfigurationService.new, ENV["IMPORT_PAAS_INSTANCE"])
       archive_io = s3_service.get_file_io(path)
       archive_service = Storage::ArchiveService.new(archive_io)
diff --git a/spec/lib/tasks/data_import_field_spec.rb b/spec/lib/tasks/data_import_field_spec.rb
index aaed8d990..c896c431f 100644
--- a/spec/lib/tasks/data_import_field_spec.rb
+++ b/spec/lib/tasks/data_import_field_spec.rb
@@ -188,6 +188,18 @@ describe "data_import_field imports" do
         end
       end
 
+      context "and we update the old_form_id field" do
+        let(:field) { "old_form_id" }
+
+        it "updates the 2023 logs from the given XML file" do
+          expect(Storage::S3Service).to receive(:new).with(paas_config_service, instance_name)
+          expect(storage_service).to receive(:get_file_io).with("spec/fixtures/imports/logs")
+          expect(Imports::LettingsLogsFieldImportService).to receive(:new).with(archive_service)
+          expect(import_service).to receive(:update_field).with(field, "logs")
+          task.invoke(field, fixture_path)
+        end
+      end
+
       it "raises an exception if no parameters are provided" do
         expect { task.invoke }.to raise_error(/Usage/)
       end
diff --git a/spec/services/imports/lettings_logs_field_import_service_spec.rb b/spec/services/imports/lettings_logs_field_import_service_spec.rb
index 60f765c26..52390e357 100644
--- a/spec/services/imports/lettings_logs_field_import_service_spec.rb
+++ b/spec/services/imports/lettings_logs_field_import_service_spec.rb
@@ -1417,4 +1417,37 @@ RSpec.describe Imports::LettingsLogsFieldImportService do
       end
     end
   end
+
+  context "when updating old_form_id" do
+    let(:field) { "old_form_id" }
+    let(:lettings_log) { LettingsLog.find_by(old_id: lettings_log_id) }
+
+    context "when the lettings log has no old_form_id value" do
+      before do
+        Imports::LettingsLogsImportService.new(storage_service, logger).create_logs(fixture_directory)
+        lettings_log_file.rewind
+        lettings_log.update!(old_form_id: nil)
+      end
+
+      it "updates the lettings_log old_form_id value" do
+        expect(logger).to receive(:info).with("lettings log #{lettings_log.id}'s old_form_id value has been set to 5786509")
+        expect { import_service.send(:update_field, field, remote_folder) }
+          .to(change { lettings_log.reload.old_form_id }.from(nil).to(5_786_509))
+      end
+    end
+
+    context "when the lettings log has a different old_form_id value" do
+      before do
+        Imports::LettingsLogsImportService.new(storage_service, logger).create_logs(fixture_directory)
+        lettings_log_file.rewind
+        lettings_log.update!(old_form_id: 123)
+      end
+
+      it "does not update the lettings_log old_form_id value" do
+        expect(logger).to receive(:info).with(/lettings log \d+ has a value for old_form_id, skipping update/)
+        expect { import_service.send(:update_field, field, remote_folder) }
+          .not_to(change { lettings_log.reload.old_form_id })
+      end
+    end
+  end
 end