diff --git a/t5x/export_lib.py b/t5x/export_lib.py
index dfb9296ae..5acc0ed10 100644
--- a/t5x/export_lib.py
+++ b/t5x/export_lib.py
@@ -309,6 +309,8 @@ def create_inference_function(
     output_len: Optional[int] = None,
 ) -> Callable[[Mapping[str, Any], Any], PyTree]:
   """Fetches a model and returns the inference function based on inference_mode."""
+  # Always use native serialization. The non-native serialization is deprecated.
+  del native_lowering
   if partitioner and train_state_initializer:
     maybe_partition = lambda fn: partitioner.partition(  # pylint:disable=g-long-lambda
         fn,
@@ -390,13 +392,12 @@ def model_fn(
         if jax2tf_disable_platform_checks
         else []
     )
-    if native_lowering and (not native_lowering_platforms):
+    if not native_lowering_platforms:
       # Change default value to make the exported cpu model still work.
       native_lowering_platforms = ['cpu', 'tpu']
     model_fn = jax2tf.convert(
         model_fn,
         polymorphic_shapes=[None, polymorphic_shapes_inputs],
-        native_serialization=native_lowering,
         native_serialization_platforms=native_lowering_platforms,
         native_serialization_disabled_checks=disabled_checks,
         enable_xla=enable_xla,
@@ -1517,8 +1518,7 @@ def save(
     validation_examples: Optional list of validation examples. If proveded, they
       will be used to validate the latency and numeric accuracy of the TPU saved
       model.
-    native_lowering: for experimental purposes only -- if True, don't convert
-      Jax fns to TF fns.
+    native_lowering: deprecated, always True.
     native_lowering_platforms: In conjunction with `native_lowering`, specify
       the platform(s) for which to lower the code. Must be a tuple of strings,
       including a subset of: 'cpu', 'cuda', 'rocm', 'tpu'. The default
@@ -1538,6 +1538,8 @@ def save(
     create_polymorphic_shapes_fn: Optional function to create polymorphic shapes
       for input tensors to the JAX model function.
   """  # fmt: skip
+  # Always use native serialization. The non-native serialization is deprecated.
+  del native_lowering
   jax.monitoring.record_event('/jax/t5x/export/beacon')
   output_dirs = _standardize_output_dirs(output_dir)
   del output_dir
@@ -1584,7 +1586,7 @@ def save(
   if create_decoding_state_callback_fn is not None:
     decoding_state_callback_fn = create_decoding_state_callback_fn(
         vocab=output_vocab,
-        call_tf_graph=native_lowering,
+        call_tf_graph=True,
     )
 
   model_tf_fn = create_inference_function_fn(
@@ -1598,7 +1600,7 @@ def save(
       polymorphic_shapes_inputs=create_polymorphic_shapes_fn(
           input_signature, preprocessor
       ),
-      native_lowering=native_lowering,
+      native_lowering=True,
       native_lowering_platforms=native_lowering_platforms,
   )