diff --git a/litellm/llms/anthropic/chat/transformation.py b/litellm/llms/anthropic/chat/transformation.py
index 82eccee596d..7879e191c3c 100644
--- a/litellm/llms/anthropic/chat/transformation.py
+++ b/litellm/llms/anthropic/chat/transformation.py
@@ -817,6 +817,8 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
                         "sonnet-4-5",
                         "opus-4.1",
                         "opus-4-1",
+                        "opus-4-6",
+                        "opus-4.6",
                     }
                 ):
                     _output_format = (