diff --git a/sdk/basyx/aas/adapter/json/json_serialization.py b/sdk/basyx/aas/adapter/json/json_serialization.py
index 0817f2bac..155aced55 100644
--- a/sdk/basyx/aas/adapter/json/json_serialization.py
+++ b/sdk/basyx/aas/adapter/json/json_serialization.py
@@ -708,7 +708,7 @@ def _entity_to_json(cls, obj: model.Entity) -> Dict[str, object]:
             data["entityType"] = _generic.ENTITY_TYPES[obj.entity_type]
         if obj.global_asset_id is not None:
             data["globalAssetId"] = obj.global_asset_id
-        if obj.specific_asset_id is not None:
+        if obj.specific_asset_id:
             data["specificAssetIds"] = list(obj.specific_asset_id)
         return data
 
diff --git a/sdk/test/adapter/json/test_json_serialization.py b/sdk/test/adapter/json/test_json_serialization.py
index e53cf6041..1fb2748fd 100644
--- a/sdk/test/adapter/json/test_json_serialization.py
+++ b/sdk/test/adapter/json/test_json_serialization.py
@@ -68,6 +68,26 @@ def test_random_object_serialization(self) -> None:
         json.loads(json_data)
 
 
+    def test_entity_omits_empty_specific_asset_ids(self) -> None:
+        # An Entity without specific asset ids must leave specificAssetIds out
+        # entirely: the schema gives it minItems 1, so an empty array is invalid.
+        # AASd-014 forbids them on a co-managed entity, so this is every such entity.
+        entity = model.Entity("test_entity", model.EntityType.CO_MANAGED_ENTITY)
+        data = json.loads(json.dumps(entity, cls=AASToJsonEncoder))
+        self.assertNotIn("specificAssetIds", data)
+
+    def test_entity_serializes_specific_asset_ids(self) -> None:
+        # AASd-014: only a self-managed entity may carry specific asset ids
+        entity = model.Entity(
+            "test_entity",
+            model.EntityType.SELF_MANAGED_ENTITY,
+            specific_asset_id=[model.SpecificAssetId("test_name", "test_value")],
+        )
+        data = json.loads(json.dumps(entity, cls=AASToJsonEncoder))
+        self.assertEqual(1, len(data["specificAssetIds"]))
+        self.assertEqual("test_name", data["specificAssetIds"][0]["name"])
+
+
 class JsonSerializationSchemaTest(unittest.TestCase):
     @classmethod
     def setUpClass(cls):