diff --git a/utils/allowed_files.py b/utils/allowed_files.py
new file mode 100644
index 0000000..61ca604
--- /dev/null
+++ b/utils/allowed_files.py
@@ -0,0 +1,2 @@
+def allowed_excel(filename):
+    return '.' in filename and filename.rsplit('.', 1)[1].lower() in {'xlsx', 'xls'}
\ No newline at end of file