diff --git a/main.py b/main.py
index ec7c8e7..7506b6b 100644
--- a/main.py
+++ b/main.py
@@ -379,7 +379,9 @@ def add_id_to_local_song_if_available_in_ct(
     logging.info("Starting add_id_to_local_song_if_available_in_ct()")
     logging.critical(
         "This function might destroy your data in case a songname exists twice in one songbook #13"
-    )  # 13 TODO
+    )
+    # TODO (bensteUEM):  Extend functionality of add_id_to_local_song_if_available_in_ct()
+    # https://github.com/bensteUEM/SongBeamerQS/issues/13
 
     compare_by_id_df = validate_ct_songs_exist_locally_by_id(df_ct, df_sng)
 
diff --git a/testData/Test/sample_no_ct.sng b/testData/Test/sample_no_ct.sng
index 42fff11..ad11af3 100644
--- a/testData/Test/sample_no_ct.sng
+++ b/testData/Test/sample_no_ct.sng
@@ -1,8 +1,8 @@
-#LangCount=1
-#Editor=Benedict's Python Script am 2023-01-22
+#LangCount=1
+#Editor=Benedict's Python Script am 2024-05-06
 #Version=3
-#Title=Test
-#Author=TestAuthor
+#Title=sample_no_ct
+#Author=Benedict
 #BackgroundImage=_ChurchMediaDrop\Dan-Stevers_Ascent_Stills\smeary clouds_4k.jpg
 #VerseOrder=Intro,Vers 1,STOP
 #Songbook= 
@@ -12,3 +12,8 @@ Intro
 ---
 Vers 1
 This file can be used for any testing that has valid data but no ChurchTools id yet
+used in test_main.py
+* test_add_id_to_local_song_if_available_in_ct
+* test_upload_new_local_songs_and_generate_ct_id
+* test_upload_local_songs_by_id
+* test_apply_ct_song_sng_count_qs_tag
diff --git a/test_main.py b/test_main.py
index ecaaffb..56a505d 100644
--- a/test_main.py
+++ b/test_main.py
@@ -14,6 +14,7 @@
 
 import SNG_DEFAULTS
 from main import (
+    add_id_to_local_song_if_available_in_ct,
     apply_ct_song_sng_count_qs_tag,
     check_ct_song_categories_exist_as_folder,
     download_missing_online_songs,
@@ -200,12 +201,24 @@ def test_emptied_song(self) -> None:
 
     def test_add_id_to_local_song_if_available_in_ct(self) -> None:
         """This should verify that add_id_to_local_song_if_available_in_ct is working as expected."""
-        self.assertFalse(
-            True,
-            "Not Implemented see https://github.com/bensteUEM/SongBeamerQS/issues/13",
-        )
-        # TODO (bensteUEM): implement test_add_id_to_local_song_if_available_in_ct
-        # https://github.com/bensteUEM/SongBeamerQS/issues/13
+        test_dir = Path("./testData/Test")
+        test_filename = "sample_no_ct.sng"
+        copyfile(test_dir / test_filename, test_dir / (test_filename + "_bak"))
+        song = SngFile(test_dir / test_filename)
+        self.assertNotIn("id", song.header)
+
+        test_local_df = pd.DataFrame([song], columns=["SngFile"])
+        test_local_df["filename"] = test_filename
+        test_local_df["path"] = test_dir
+
+        test_ct_id = 3064
+        test_ct_df = pd.json_normalize(self.api.get_songs(song_id=test_ct_id))
+
+        add_id_to_local_song_if_available_in_ct(df_sng=test_local_df, df_ct=test_ct_df)
+        self.assertEqual(song.header["id"], str(test_ct_id))
+
+        # cleanup
+        (test_dir / (test_filename + "_bak")).rename(test_dir / test_filename)
 
     def test_download_missing_online_songs(self) -> None:
         """ELKW1610.krz.tools specific test case for the named function (using 2 specific song IDs).