diff --git a/app/services/imports/sales_logs_field_import_service.rb b/app/services/imports/sales_logs_field_import_service.rb
new file mode 100644
index 000000000..5aafd29e3
--- /dev/null
+++ b/app/services/imports/sales_logs_field_import_service.rb
@@ -0,0 +1,37 @@
+module Imports
+  class SalesLogsFieldImportService < LogsImportService
+    def update_field(field, folder)
+      case field
+      when "creation_method"
+        import_from(folder, :update_creation_method)
+      else
+        raise "Updating #{field} is not supported by the field import service"
+      end
+    end
+
+  private
+
+    def update_creation_method(xml_doc)
+      old_id = meta_field_value(xml_doc, "document-id")
+      log = SalesLog.find_by(old_id:)
+
+      if log
+        upload_method = meta_field_value(xml_doc, "upload-method")
+
+        case upload_method
+        when "Manual Entry"
+          @logger.info "sales log with old id #{old_id} entered manually, no need for update"
+        when "Bulk Upload"
+          if log.creation_method == "bulk upload"
+            @logger.info "sales log #{log.id} creation method already set to bulk upload, no need for update"
+          else
+            log.update!(creation_method: "bulk upload")
+            @logger.info "sales log #{log.id} creation method set to bulk upload"
+          end
+        end
+      else
+        @logger.warn "sales log with old id #{old_id} not found"
+      end
+    end
+  end
+end
diff --git a/spec/services/imports/sales_logs_field_import_service_spec.rb b/spec/services/imports/sales_logs_field_import_service_spec.rb
new file mode 100644
index 000000000..799c66da8
--- /dev/null
+++ b/spec/services/imports/sales_logs_field_import_service_spec.rb
@@ -0,0 +1,76 @@
+require "rails_helper"
+
+RSpec.describe Imports::SalesLogsFieldImportService do
+  subject(:import_service) { described_class.new(storage_service, logger) }
+
+  let(:storage_service) { instance_double(Storage::S3Service) }
+  let(:logger) { instance_double(ActiveSupport::Logger) }
+
+  let(:fixture_directory) { "spec/fixtures/imports/sales_logs" }
+  let(:sales_log_filename) { "shared_ownership_sales_log" }
+  let(:sales_log_file) { File.open("#{fixture_directory}/#{sales_log_filename}.xml") }
+  let(:organisation) { create(:organisation, old_visible_id: "1") }
+  let(:old_user_id) { "c3061a2e6ea0b702e6f6210d5c52d2a92612d2aa" }
+
+  let(:remote_folder) { "sales_logs" }
+
+  before do
+    create(:user, old_user_id:, organisation:)
+
+    allow(storage_service)
+      .to receive(:list_files)
+      .and_return(["#{sales_log_filename}.xml"])
+    allow(storage_service)
+      .to receive(:get_file_io)
+      .with("#{sales_log_filename}.xml")
+      .and_return(sales_log_file)
+  end
+
+  context "when updating bulk upload id" do
+    let(:field) { "creation_method" }
+    let(:sales_log) { SalesLog.find_by(old_id: sales_log_filename) }
+
+    before do
+      Imports::SalesLogsImportService.new(storage_service, logger).create_logs(fixture_directory)
+      sales_log_file.rewind
+    end
+
+    context "and the log was manually entered" do
+      let(:sales_log_filename) { "shared_ownership_sales_log" }
+
+      it "logs that bulk upload id does not need setting" do
+        expect(logger).to receive(:info).with("sales log with old id #{sales_log_filename} entered manually, no need for update")
+        expect { import_service.update_field(field, remote_folder) }.not_to(change { sales_log.reload.creation_method })
+      end
+    end
+
+    context "and the log was bulk uploaded and the creation method is already correct" do
+      let(:sales_log_filename) { "shared_ownership_sales_log2" }
+
+      it "logs that bulk upload id does not need setting" do
+        expect(logger).to receive(:info).with(/sales log \d+ creation method already set to bulk upload, no need for update/)
+        expect { import_service.update_field(field, remote_folder) }.not_to(change { sales_log.reload.creation_method })
+      end
+    end
+
+    context "and the log was bulk uploaded and the creation method requires updating" do
+      let(:sales_log_filename) { "shared_ownership_sales_log2" }
+
+      it "logs that bulk upload id does not need setting" do
+        sales_log.update!(creation_method: "single log")
+        expect(logger).to receive(:info).with(/sales log \d+ creation method set to bulk upload/)
+        expect { import_service.update_field(field, remote_folder) }.to change { sales_log.reload.creation_method }.to "bulk upload"
+      end
+    end
+
+    context "and the log was not previously imported" do
+      let(:sales_log_filename) { "shared_ownership_sales_log" }
+
+      it "logs a warning that the log has not been found in the db" do
+        sales_log.destroy!
+        expect(logger).to receive(:warn).with("sales log with old id #{sales_log_filename} not found")
+        import_service.update_field(field, remote_folder)
+      end
+    end
+  end
+end