diff --git a/litellm/proxy/proxy_server.py b/litellm/proxy/proxy_server.py
index d4ad0834d..252ccafa7 100644
--- a/litellm/proxy/proxy_server.py
+++ b/litellm/proxy/proxy_server.py
@@ -118,6 +118,37 @@ def data_generator(response):
         print_verbose(f"returned chunk: {chunk}")
         yield f"data: {json.dumps(chunk)}\n\n"
 
+def custom_callback(
+    kwargs,                 # kwargs to completion
+    completion_response,    # response from completion
+    start_time, end_time    # start/end time
+):
+    # Your custom code here
+    print("LITELLM: in custom callback function")
+    # print("kwargs", kwargs)
+    # print("start_time", start_time)
+    # print("end_time", end_time)
+    if "complete_streaming_response" in kwargs:
+        print("GOT COMPLETE STREAMING RESPINSE", kwargs["complete_streaming_response"])
+        response_cost = litellm.completion_cost(
+            completion_response=kwargs["complete_streaming_response"]
+        )
+        print("response_cost", response_cost)
+    else:
+        print("completion_response", completion_response)
+        response_cost = litellm.completion_cost(completion_response=completion_response)
+
+    logging.basicConfig(
+            filename='cost.log',
+            level=logging.INFO,
+            format='%(asctime)s - %(message)s',
+            datefmt='%Y-%m-%d %H:%M:%S'
+    )
+    logging.info(f"Model {completion_response.model} Cost: ${response_cost:.8f}")
+
+
+litellm.success_callback = [custom_callback]
+
 def litellm_completion(data, type): 
     try: 
         if user_model:
@@ -203,22 +234,8 @@ async def chat_completion(request: Request):
     data = await request.json()
     print_verbose(f"data passed in: {data}")
     response = litellm_completion(data, type="chat_completion")
-    # track cost of this response, using litellm.completion_cost
-    track_cost(response)
     return response
 
-async def track_cost(response):
-    try:
-        logging.basicConfig(
-            filename='cost.log',
-            level=logging.INFO,
-            format='%(asctime)s - %(message)s',
-            datefmt='%Y-%m-%d %H:%M:%S'
-        )
-        response_cost = litellm.completion_cost(completion_response=response)
-        logging.info(f"Model {response.model} Cost: ${response_cost:.8f}")
-    except:
-        pass
 
 def print_cost_logs():
     with open('cost.log', 'r') as f: