diff --git a/litellm/llms/anthropic/common_utils.py b/litellm/llms/anthropic/common_utils.py
index e36658825b1..d1ad32ee0a8 100644
--- a/litellm/llms/anthropic/common_utils.py
+++ b/litellm/llms/anthropic/common_utils.py
@@ -1254,9 +1254,7 @@ class AnthropicModelInfo(BaseLLMModelInfo):
         wif_minted: bool = False,
         context_1m_requested: bool = False,
     ) -> dict:
-        betas: Final[set[str]] = set()
-        if context_1m_requested:
-            betas.add(ANTHROPIC_BETA_HEADER_VALUES.CONTEXT_1M_2025_08_07.value)
+        betas: Final = set()
         # Anthropic no longer requires the prompt-caching beta header
         # Prompt caching now works automatically when cache_control is used in messages
         # Reference: https://docs.anthropic.com/en/docs/build-with-claude/prompt-caching
@@ -1313,6 +1311,7 @@ class AnthropicModelInfo(BaseLLMModelInfo):
             betas.update(user_anthropic_beta_headers)
 
         all_betas: Final = betas.union(
+            (ANTHROPIC_BETA_HEADER_VALUES.CONTEXT_1M_2025_08_07.value,) if context_1m_requested else (),
             (ANTHROPIC_THINKING_DISPLAY_UPDATES_BETA_HEADER,) if is_thinking_display_updates_used else (),
             (ANTHROPIC_MID_CONVERSATION_TOOL_CHANGES_BETA_HEADER,) if is_mid_conversation_tool_change_used else (),
         )
diff --git a/tests/unit/llms/anthropic/chat/test_anthropic_chat_transformation.py b/tests/unit/llms/anthropic/chat/test_anthropic_chat_transformation.py
index 6fe5be19fb9..41879e67654 100644
--- a/tests/unit/llms/anthropic/chat/test_anthropic_chat_transformation.py
+++ b/tests/unit/llms/anthropic/chat/test_anthropic_chat_transformation.py
@@ -9827,14 +9827,17 @@ def test_transform_request_treats_context_1m_model_as_its_base_model(optional_pa
             headers={},
         )
 
-    assert transform("claude-sonnet-4-6[1m]") == transform("claude-sonnet-4-6")
+    assert transform("claude-sonnet-5-5[1m]") == transform("claude-sonnet-5-5")
 
 
 @pytest.mark.parametrize(
     "model,expected_betas",
     [
-        ("anthropic/claude-sonnet-4-6[1m]", {"context-1m-2025-08-07", "interleaved-thinking-2025-05-14"}),
-        ("anthropic/claude-sonnet-4-6", {"interleaved-thinking-2025-05-14"}),
+        (
+            "anthropic/claude-sonnet-5-5[1m]",
+            {ANTHROPIC_BETA_HEADER_VALUES.CONTEXT_1M_2025_08_07.value, "interleaved-thinking-2025-05-14"},
+        ),
+        ("anthropic/claude-sonnet-5-5", {"interleaved-thinking-2025-05-14"}),
     ],
 )
 async def test_acompletion_context_1m_suffix_sends_base_model_with_beta(
@@ -9852,7 +9855,7 @@ async def test_acompletion_context_1m_suffix_sends_base_model_with_beta(
             "id": "msg_context_1m",
             "type": "message",
             "role": "assistant",
-            "model": "claude-sonnet-4-6",
+            "model": "claude-sonnet-5-5",
             "content": [{"type": "text", "text": "hi"}],
             "stop_reason": "end_turn",
             "usage": {"input_tokens": 1, "output_tokens": 1},
@@ -9867,5 +9870,5 @@ async def test_acompletion_context_1m_suffix_sends_base_model_with_beta(
     )
 
     request: Final = route.calls.last.request
-    assert json.loads(request.content)["model"] == "claude-sonnet-4-6"
+    assert json.loads(request.content)["model"] == "claude-sonnet-5-5"
     assert {beta.strip() for beta in request.headers["anthropic-beta"].split(",")} == expected_betas
diff --git a/tests/unit/llms/anthropic/pass_through/messages/test_anthropic_messages_context_1m.py b/tests/unit/llms/anthropic/pass_through/messages/test_anthropic_messages_context_1m.py
index 4525769a7cf..0b5a8bec354 100644
--- a/tests/unit/llms/anthropic/pass_through/messages/test_anthropic_messages_context_1m.py
+++ b/tests/unit/llms/anthropic/pass_through/messages/test_anthropic_messages_context_1m.py
@@ -6,13 +6,36 @@ import respx
 
 import litellm
 from litellm import Router
+from litellm.llms.anthropic.pass_through.messages.transformation import AnthropicMessagesConfig
+from litellm.types.llms.anthropic import ANTHROPIC_BETA_HEADER_VALUES
+
+
+@pytest.mark.parametrize("model,expects_context_1m", [("claude-sonnet-5-5[1m]", True), ("claude-sonnet-5-5", False)])
+def test_sync_messages_environment_adds_context_1m_beta_only_for_suffixed_model(
+    model: str, expects_context_1m: bool
+) -> None:
+    headers, _ = AnthropicMessagesConfig().validate_anthropic_messages_environment(
+        headers={"anthropic-beta": "interleaved-thinking-2025-05-14"},
+        model=model,
+        messages=[{"role": "user", "content": "hi"}],
+        optional_params={},
+        litellm_params={},
+        api_key="test",
+    )
+
+    betas: Final = {beta.strip() for beta in headers["anthropic-beta"].split(",")}
+    assert (ANTHROPIC_BETA_HEADER_VALUES.CONTEXT_1M_2025_08_07.value in betas) is expects_context_1m
+    assert "interleaved-thinking-2025-05-14" in betas
 
 
 @pytest.mark.parametrize(
     "deployment_model,expected_betas",
     [
-        ("anthropic/claude-sonnet-4-6[1m]", {"context-1m-2025-08-07", "interleaved-thinking-2025-05-14"}),
-        ("anthropic/claude-sonnet-4-6", {"interleaved-thinking-2025-05-14"}),
+        (
+            "anthropic/claude-sonnet-5-5[1m]",
+            {ANTHROPIC_BETA_HEADER_VALUES.CONTEXT_1M_2025_08_07.value, "interleaved-thinking-2025-05-14"},
+        ),
+        ("anthropic/claude-sonnet-5-5", {"interleaved-thinking-2025-05-14"}),
     ],
 )
 async def test_router_messages_context_1m_deployment_sends_base_model_with_beta(
@@ -30,7 +53,7 @@ async def test_router_messages_context_1m_deployment_sends_base_model_with_beta(
             "id": "msg_context_1m",
             "type": "message",
             "role": "assistant",
-            "model": "claude-sonnet-4-6",
+            "model": "claude-sonnet-5-5",
             "content": [{"type": "text", "text": "hi"}],
             "stop_reason": "end_turn",
             "usage": {"input_tokens": 1, "output_tokens": 1},
@@ -39,19 +62,19 @@ async def test_router_messages_context_1m_deployment_sends_base_model_with_beta(
     router: Final = Router(
         model_list=[
             {
-                "model_name": "claude-sonnet-4-6[1m]",
+                "model_name": "claude-sonnet-5-5[1m]",
                 "litellm_params": {"model": deployment_model, "api_key": "test"},
             }
         ]
     )
 
     await router.aanthropic_messages(
-        model="claude-sonnet-4-6[1m]",
+        model="claude-sonnet-5-5[1m]",
         messages=[{"role": "user", "content": "hi"}],
         max_tokens=16,
         extra_headers={"anthropic-beta": "interleaved-thinking-2025-05-14"},
     )
 
     request: Final = route.calls.last.request
-    assert json.loads(request.content)["model"] == "claude-sonnet-4-6"
+    assert json.loads(request.content)["model"] == "claude-sonnet-5-5"
     assert {beta.strip() for beta in request.headers["anthropic-beta"].split(",")} == expected_betas
diff --git a/tests/unit/llms/anthropic/test_anthropic_common_utils.py b/tests/unit/llms/anthropic/test_anthropic_common_utils.py
index 20afc5b7e40..2ee3644dc76 100644
--- a/tests/unit/llms/anthropic/test_anthropic_common_utils.py
+++ b/tests/unit/llms/anthropic/test_anthropic_common_utils.py
@@ -4524,12 +4524,12 @@ def test_shared_legacy_thinking_translation_drops_a_non_numeric_budget_under_dro
 @pytest.mark.parametrize(
     "model,base_model",
     [
-        ("claude-sonnet-4-6[1m]", "claude-sonnet-4-6"),
-        ("claude-sonnet-4-6[1M]", "claude-sonnet-4-6"),
-        ("claude-sonnet-4-6", "claude-sonnet-4-6"),
-        ("claude-[1m]-sonnet-4-6", "claude-[1m]-sonnet-4-6"),
-        ("claude-sonnet-4-6[1m][1m]", "claude-sonnet-4-6[1m]"),
-        ("claude-sonnet-4-6[200k]", "claude-sonnet-4-6[200k]"),
+        ("claude-sonnet-5-5[1m]", "claude-sonnet-5-5"),
+        ("claude-sonnet-5-5[1M]", "claude-sonnet-5-5"),
+        ("claude-sonnet-5-5", "claude-sonnet-5-5"),
+        ("claude-[1m]-sonnet-5-5", "claude-[1m]-sonnet-5-5"),
+        ("claude-sonnet-5-5[1m][1m]", "claude-sonnet-5-5[1m]"),
+        ("claude-sonnet-5-5[200k]", "claude-sonnet-5-5[200k]"),
     ],
 )
 def test_context_1m_suffix_is_only_a_trailing_marker(model: str, base_model: str) -> None:
@@ -4539,11 +4539,12 @@ def test_context_1m_suffix_is_only_a_trailing_marker(model: str, base_model: str
     assert has_context_1m_suffix(model) is (model != base_model)
 
 
-@pytest.mark.parametrize("model,expects_context_1m", [("claude-sonnet-4-6[1m]", True), ("claude-sonnet-4-6", False)])
+@pytest.mark.parametrize("model,expects_context_1m", [("claude-sonnet-5-5[1m]", True), ("claude-sonnet-5-5", False)])
 def test_validate_environment_adds_context_1m_beta_only_for_suffixed_model(
     model: str, expects_context_1m: bool
 ) -> None:
     from litellm.llms.anthropic.common_utils import AnthropicModelInfo
+    from litellm.types.llms.anthropic import ANTHROPIC_BETA_HEADER_VALUES
 
     headers: Final = AnthropicModelInfo().validate_environment(
         headers={"anthropic-beta": "interleaved-thinking-2025-05-14"},
@@ -4555,5 +4556,5 @@ def test_validate_environment_adds_context_1m_beta_only_for_suffixed_model(
     )
 
     betas: Final = {beta.strip() for beta in headers["anthropic-beta"].split(",")}
-    assert ("context-1m-2025-08-07" in betas) is expects_context_1m
+    assert (ANTHROPIC_BETA_HEADER_VALUES.CONTEXT_1M_2025_08_07.value in betas) is expects_context_1m
     assert "interleaved-thinking-2025-05-14" in betas