diff --git a/src/crewai/crew.py b/src/crewai/crew.py
index 7c9696f6d4..3ca6ff9f72 100644
--- a/src/crewai/crew.py
+++ b/src/crewai/crew.py
@@ -720,8 +720,13 @@ async def run_crew(crew, input_data):
     def _handle_crew_planning(self):
         """Handles the Crew planning."""
         self._logger.log("info", "Planning the crew execution")
+        
+        agent_llm = self.agents[0].llm if self.agents and hasattr(self.agents[0], 'llm') else None
+        
         result = CrewPlanner(
-            tasks=self.tasks, planning_agent_llm=self.planning_llm
+            tasks=self.tasks, 
+            planning_agent_llm=self.planning_llm,
+            agent_llm=agent_llm
         )._handle_crew_planning()
 
         for task, step_plan in zip(self.tasks, result.list_of_plans_per_task):
diff --git a/src/crewai/utilities/planning_handler.py b/src/crewai/utilities/planning_handler.py
index 1bd14a0c88..3bcfc8c81a 100644
--- a/src/crewai/utilities/planning_handler.py
+++ b/src/crewai/utilities/planning_handler.py
@@ -28,11 +28,23 @@ class PlannerTaskPydanticOutput(BaseModel):
 
 class CrewPlanner:
     """Plans and coordinates the execution of crew tasks."""
-    def __init__(self, tasks: List[Task], planning_agent_llm: Optional[Any] = None):
+    def __init__(self, tasks: List[Task], planning_agent_llm: Optional[Any] = None, agent_llm: Optional[Any] = None):
         self.tasks = tasks
 
         if planning_agent_llm is None:
-            self.planning_agent_llm = "gpt-4o-mini"
+            if agent_llm is not None and hasattr(agent_llm, "base_url") and agent_llm.base_url is not None:
+                from crewai.llm import LLM
+                self.planning_agent_llm = LLM(
+                    model="gpt-4o-mini",
+                    base_url=agent_llm.base_url,
+                    api_key=getattr(agent_llm, "api_key", None),
+                    organization=getattr(agent_llm, "organization", None),
+                    api_version=getattr(agent_llm, "api_version", None),
+                    extra_headers=getattr(agent_llm, "extra_headers", None)
+                )
+            else:
+                from crewai.llm import LLM
+                self.planning_agent_llm = LLM(model="gpt-4o-mini")
         else:
             self.planning_agent_llm = planning_agent_llm
 
diff --git a/tests/utilities/test_planning_auth/__init__.py b/tests/utilities/test_planning_auth/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/tests/utilities/test_planning_auth/test_planning_auth_inheritance.py b/tests/utilities/test_planning_auth/test_planning_auth_inheritance.py
new file mode 100644
index 0000000000..c667e619b9
--- /dev/null
+++ b/tests/utilities/test_planning_auth/test_planning_auth_inheritance.py
@@ -0,0 +1,28 @@
+import unittest
+from unittest.mock import MagicMock
+
+from crewai import Task
+from crewai.utilities.planning_handler import CrewPlanner
+
+
+def test_planning_llm_inherits_auth_params():
+    """Test that planning LLM inherits authentication parameters from agent LLM."""
+    mock_llm = MagicMock()
+    mock_llm.base_url = "https://api.custom-provider.com/v1"
+    mock_llm.api_version = "2023-05-15"
+    
+    task = Task(
+        description="Test Task",
+        expected_output="Test Output"
+    )
+    
+    planner = CrewPlanner(
+        tasks=[task],
+        planning_agent_llm=None,  # This should trigger the inheritance logic
+        agent_llm=mock_llm
+    )
+    
+    assert hasattr(planner, 'planning_agent_llm')
+    assert hasattr(planner.planning_agent_llm, 'base_url')
+    assert planner.planning_agent_llm.base_url == "https://api.custom-provider.com/v1"
+    assert planner.planning_agent_llm.api_version == "2023-05-15"