diff --git a/changelog_entry.yaml b/changelog_entry.yaml
index e69de29bb..3332d2280 100644
--- a/changelog_entry.yaml
+++ b/changelog_entry.yaml
@@ -0,0 +1,4 @@
+- bump: minor
+  changes:
+    changed:
+      - Enable Modal simulation API by default instead of GCP Workflows
diff --git a/policyengine_api/libs/simulation_api_factory.py b/policyengine_api/libs/simulation_api_factory.py
index c94d1f90b..38af346d1 100644
--- a/policyengine_api/libs/simulation_api_factory.py
+++ b/policyengine_api/libs/simulation_api_factory.py
@@ -18,8 +18,8 @@
 
 
 def get_simulation_api() -> (
-    Union["SimulationAPI", "SimulationAPIModal"]  # noqa: F821
-):
+    Union["SimulationAPI", "SimulationAPIModal"]
+):  # noqa: F821
     """
     Get the appropriate simulation API client based on environment configuration.
 
@@ -37,7 +37,7 @@ def get_simulation_api() -> (
         If GCP client is requested but GOOGLE_APPLICATION_CREDENTIALS is not set.
     """
     use_modal = (
-        os.environ.get("USE_MODAL_SIMULATION_API", "false").lower() == "true"
+        os.environ.get("USE_MODAL_SIMULATION_API", "true").lower() == "true"
     )
 
     if use_modal:
diff --git a/tests/unit/libs/test_simulation_api_factory.py b/tests/unit/libs/test_simulation_api_factory.py
index 6602c47b4..9e243197a 100644
--- a/tests/unit/libs/test_simulation_api_factory.py
+++ b/tests/unit/libs/test_simulation_api_factory.py
@@ -120,36 +120,29 @@ def test__given_use_modal_env_false__then_returns_gcp_api(
                         # Then
                         assert isinstance(api, SimulationAPI)
 
-        def test__given_use_modal_env_not_set__then_returns_gcp_api(
+        def test__given_use_modal_env_not_set__then_returns_modal_api(
             self,
             mock_factory_logger,
         ):
-            # Given
+            # Given - default is now Modal when env var is not set
             import os
 
             env_copy = dict(os.environ)
             env_copy.pop("USE_MODAL_SIMULATION_API", None)
-            env_copy["GOOGLE_APPLICATION_CREDENTIALS"] = "/path/to/creds.json"
 
             with patch.dict("os.environ", env_copy, clear=True):
-                with patch(
-                    "policyengine_api.libs.simulation_api.executions_v1.ExecutionsClient"
-                ):
-                    with patch(
-                        "policyengine_api.libs.simulation_api.workflows_v1.WorkflowsClient"
-                    ):
-                        from policyengine_api.libs.simulation_api_factory import (
-                            get_simulation_api,
-                        )
-                        from policyengine_api.libs.simulation_api import (
-                            SimulationAPI,
-                        )
+                from policyengine_api.libs.simulation_api_factory import (
+                    get_simulation_api,
+                )
+                from policyengine_api.libs.simulation_api_modal import (
+                    SimulationAPIModal,
+                )
 
-                        # When
-                        api = get_simulation_api()
+                # When
+                api = get_simulation_api()
 
-                        # Then
-                        assert isinstance(api, SimulationAPI)
+                # Then
+                assert isinstance(api, SimulationAPIModal)
 
         def test__given_use_modal_env_false__then_logs_gcp_selection(
             self,
@@ -189,11 +182,11 @@ def test__given_gcp_selected_without_credentials__then_raises_error(
             self,
             mock_factory_logger,
         ):
-            # Given
+            # Given - explicitly select GCP without credentials
             import os
 
             env_copy = dict(os.environ)
-            env_copy.pop("USE_MODAL_SIMULATION_API", None)
+            env_copy["USE_MODAL_SIMULATION_API"] = "false"
             env_copy.pop("GOOGLE_APPLICATION_CREDENTIALS", None)
 
             with patch.dict("os.environ", env_copy, clear=True):