diff --git a/returnn/tf/layers/base.py b/returnn/tf/layers/base.py
index 9674923436..dd3b579d52 100644
--- a/returnn/tf/layers/base.py
+++ b/returnn/tf/layers/base.py
@@ -11,7 +11,7 @@
 from returnn.util.basic import NotSpecified, CollectionReadCheckCovered, BehaviorVersion
 import returnn.tf.compat as tf_compat
 import returnn.tf.util.basic as tf_util
-from returnn.tf.util.data import Data, SearchBeam
+from returnn.tf.util.data import Data
 from returnn.tf.util.basic import OutputWithActivation, CustomUpdate, reuse_name_scope
 from returnn.log import log
 
@@ -255,6 +255,7 @@ def _base_get_out_data_from_opts(cls, network, name, out_type=None, n_out=NotSpe
     :return: Data template (placeholder not set)
     :rtype: Data
     """
+    from ..util.data import DimensionTag
     if callable(out_type):
       return out_type(
         network=network, name=name, n_out=n_out, target=target, size_target=size_target, sources=sources, loss=loss,
@@ -273,9 +274,8 @@ def _base_get_out_data_from_opts(cls, network, name, out_type=None, n_out=NotSpe
         network=network, mark_data_key_as_used=False).dim
     if n_out is not NotSpecified:
       assert out_type["dim"] == n_out
-    sources_data = None
-    if sources and sources[0]:
-      sources_data = sources[0].output.copy_template()
+    sources_data_list = [src.output for src in sources if src]
+    sources_data = Data.get_common_data(sources_data_list, ignore_feature_dim=True) if sources_data_list else None
     if sources_data and not sources_data.sparse and not out_type.get("sparse", False):
       out_type.setdefault("dtype", sources_data.dtype)
     # You are supposed to set self.output.{batch_dim_axis,time_dim_axis} explicitly,
@@ -296,38 +296,30 @@ def _base_get_out_data_from_opts(cls, network, name, out_type=None, n_out=NotSpe
     if "shape" not in out_type and "dim_tags" not in out_type:
       if sources_data:
         if out_type.get("sparse", False):
-          out_type.setdefault("shape", sources_data.shape_sparse)
+          out_type["dim_tags"] = sources_data.dim_tags_sparse
         else:  # not sparse
           feature_dim_axis = out_type.get("feature_dim_axis", NotSpecified)
-          if feature_dim_axis is NotSpecified:
-            if sources_data.feature_dim_axis is not None:
-              feature_dim_axis = sources_data.feature_dim_axis
-            else:
-              feature_dim_axis = -1
-          if sources_data.shape:
-            default_shape = list(sources_data.shape_dense)
-            if sources_data.batch_dim_axis is not None:
-              default_shape.insert(sources_data.batch_dim_axis, None)
-            default_shape[feature_dim_axis] = out_type.get("dim", None)
-            if out_type.get("batch_dim_axis") is not None:
-              default_shape.pop(out_type.get("batch_dim_axis"))
-          else:  # source is scalar
-            if out_type.get("dim") or out_type.get("feature_dim_axis") is not None:
-              default_shape = (out_type.get("dim"),)
+          dim = out_type.get("dim", None)
+          dim_tags = list(sources_data.dim_tags_sparse)
+          feature_dim_tag = DimensionTag(
+            kind=DimensionTag.Types.Feature, description="%s:feature-dense" % name, dimension=dim)
+          if feature_dim_axis in (NotSpecified, None):
+            if sources_data.feature_dim_axis is None:
+              feature_dim_axis = len(dim_tags)
             else:
-              default_shape = ()
-          out_type.setdefault("shape", tuple(default_shape))
+              feature_dim_axis = sources_data.feature_dim_axis
+          dim_tags.insert(feature_dim_axis, feature_dim_tag)
+          out_type["dim_tags"] = dim_tags
       elif network.is_inside_rec_layer():
         if out_type.get("sparse", False):
           out_type.setdefault("shape", ())
         else:
           out_type.setdefault("shape", (out_type.get("dim", None),))
     # Note: No special handling for feature_dim_axis here for now...
-    beam = None
-    for src in sources:
-      if src:  # might be None if template construction
-        beam = SearchBeam.get_combined_beam(beam, src.output.beam)
-    out_type.setdefault("beam", beam)
+    if sources_data and sources_data.batch:
+      out_type.setdefault("batch", sources_data.batch)
+    if sources_data and sources_data.beam:
+      out_type.setdefault("beam", sources_data.beam)
     output = Data(**out_type)
     cls._post_init_output(
       output=output, network=network, target=target, size_target=size_target, _target_layers=_target_layers,
diff --git a/returnn/tf/util/data.py b/returnn/tf/util/data.py
index ffa8e7ca93..8aee5ed70e 100644
--- a/returnn/tf/util/data.py
+++ b/returnn/tf/util/data.py
@@ -2343,23 +2343,23 @@ def shape_dense(self):
     return self.shape
 
   @property
-  def shape_sparse(self):
+  def batch_shape_dense(self):
     """
-    :return: shape without feature dim axis
     :rtype: tuple[int|None]
     """
     if self.sparse:
-      return self.shape
-    return self.shape[:self.feature_dim_axis] + self.shape[self.feature_dim_axis + 1:]
+      return self.batch_shape + (self.dim,)
+    return self.batch_shape
 
   @property
-  def batch_shape_dense(self):
+  def dim_tags_sparse(self):
     """
-    :rtype: tuple[int|None]
+    :return: dim tags without feature dim axis
+    :rtype: tuple[DimensionTag]
     """
-    if self.sparse:
-      return self.batch_shape + (self.dim,)
-    return self.batch_shape
+    if self.sparse or not self.have_feature_axis():
+      return self.dim_tags
+    return self.dim_tags[:self.feature_dim_axis] + self.dim_tags[self.feature_dim_axis + 1:]
 
   @property
   def ndim(self):