diff --git a/backend/tests/test_robust_boundary_file_size.py b/backend/tests/test_robust_boundary_file_size.py
new file mode 100644
index 0000000..263f31c
--- /dev/null
+++ b/backend/tests/test_robust_boundary_file_size.py
@@ -0,0 +1,17 @@
+"""
+TC_003 - Robust boundary test for file size above maximum size
+"""
+def test_file_size_robust_boundary(self):
+  # Creates a file with invalid size
+  invalid_above_file = SimpleUploadedFile("test_above_max.txt", b"x" * (max_size + 1)) 
+  # Creates AthleteFile object with the invalid file
+  athlete_above_file = AthleteFile(athlete=self.user, owner=self.user, file=invalid_above_file)
+
+  try:
+    # Runs a validation check
+    athlete_above_file.full_clean()
+    # Fails if no validation errors are raised
+    self.fail("ValidationError not raised for file above maximum size.")
+  except ValidationError as e:
+    # Passes if validation error is raised.
+    self.assertIn('file', e.message_dict)