diff --git a/litellm/litellm_core_utils/get_litellm_params.py b/litellm/litellm_core_utils/get_litellm_params.py
index b8c3f1917b0..f4ae597792c 100644
--- a/litellm/litellm_core_utils/get_litellm_params.py
+++ b/litellm/litellm_core_utils/get_litellm_params.py
@@ -50,6 +50,11 @@ ANTHROPIC_WIF_KWARGS_KEYS: Final = frozenset(
         "anthropic_keycloak_auth_method",
         "anthropic_keycloak_client_secret_ref",
         "anthropic_keycloak_scope",
+        # Set server-side when a client redirects api_base, to stop a federated deployment minting
+        # for a base the caller chose. It has to ride this funnel or it is dropped on the way and
+        # the deployment federates anyway; being carried here also request-bans it, which is right,
+        # since a caller must not be able to set it in either direction.
+        "anthropic_disable_workload_identity_federation",
     }
 )
 
diff --git a/litellm/types/router.py b/litellm/types/router.py
index c51e4ecbc27..6e5686f0165 100644
--- a/litellm/types/router.py
+++ b/litellm/types/router.py
@@ -297,6 +297,9 @@ class CredentialLiteLLMParams(BaseModel):
     anthropic_keycloak_auth_method: str | None = None
     anthropic_keycloak_client_secret_ref: str | None = None
     anthropic_keycloak_scope: str | None = None
+    # Server-set when a client redirects api_base. Declared so it survives the strict dump the
+    # other federation fields above are declared for, rather than being rebuilt away in transit.
+    anthropic_disable_workload_identity_federation: bool | None = None
 
 
 def anthropic_wif_fields_present(fields: Mapping[str, object]) -> tuple[str, ...]:
diff --git a/tests/test_litellm/llms/anthropic/test_anthropic_common_utils.py b/tests/test_litellm/llms/anthropic/test_anthropic_common_utils.py
index 12d97b200ae..d3ae04eea2d 100644
--- a/tests/test_litellm/llms/anthropic/test_anthropic_common_utils.py
+++ b/tests/test_litellm/llms/anthropic/test_anthropic_common_utils.py
@@ -3426,6 +3426,28 @@ class TestWifServerOwnedParamsAreUnconditional:
 
 
 class TestWifDisabledOnClientRedirectedBase:
+    def test_the_sentinel_survives_the_kwargs_funnel(self):
+        """Setting the sentinel is only half of it. get_litellm_params rebuilds litellm_params from
+        kwargs, so a field it does not carry is dropped on the way and the deployment federates for
+        the caller-chosen base after all."""
+        from litellm.litellm_core_utils.get_litellm_params import FORWARDED_KWARGS_KEYS
+        from litellm.router_utils.clientside_credential_handler import (
+            DISABLE_WORKLOAD_IDENTITY_PARAM,
+        )
+
+        assert DISABLE_WORKLOAD_IDENTITY_PARAM in FORWARDED_KWARGS_KEYS
+
+    def test_the_sentinel_is_not_client_settable(self):
+        """It is server-owned in both directions: a caller must not be able to set it, and must not
+        be able to clear it either."""
+        from litellm.router_utils.clientside_credential_handler import (
+            DISABLE_WORKLOAD_IDENTITY_PARAM,
+        )
+        from litellm.types.router import reject_server_owned_wif_params
+
+        with pytest.raises(ValueError, match=DISABLE_WORKLOAD_IDENTITY_PARAM):
+            reject_server_owned_wif_params({DISABLE_WORKLOAD_IDENTITY_PARAM: False})
+
     def test_base_override_clears_wif_and_sets_the_sentinel(self):
         """A federation token minted for a client-chosen api_base would send the workload's assertion,
         and then the minted bearer, to that host."""
diff --git a/tests/test_litellm/types/test_router.py b/tests/test_litellm/types/test_router.py
index c0e77e5867b..f377a59f21c 100644
--- a/tests/test_litellm/types/test_router.py
+++ b/tests/test_litellm/types/test_router.py
@@ -109,6 +109,7 @@ def test_credential_litellm_params_declares_every_anthropic_wif_field():
 def test_anthropic_wif_fields_round_trip_through_model_dump():
     values = {field: f"value-for-{field}" for field in anthropic_wif_litellm_params}
     values["anthropic_issuer_ttl_seconds"] = 300
+    values["anthropic_disable_workload_identity_federation"] = True
 
     dumped = CredentialLiteLLMParams(**values).model_dump(exclude_none=True)