diff --git a/CHANGES.md b/CHANGES.md
index 4a87dedbf..981ac9d9b 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -6,6 +6,9 @@ releases are available on [Anaconda.org](https://anaconda.org/conda-forge/gettsi
 
 ## Unpublished
 
+- {gh}`1050` Allow input template creation when path to root node traverses an
+  automatically created function ({ghuser}`MImmesberger`)
+
 - {gh}`1048` Raise an error if invalid input paths are provided to main
   ({ghuser}`hmgaudecker`)
 
diff --git a/src/ttsim/interface_dag_elements/templates.py b/src/ttsim/interface_dag_elements/templates.py
index 3e5408df1..0c8c98cc6 100644
--- a/src/ttsim/interface_dag_elements/templates.py
+++ b/src/ttsim/interface_dag_elements/templates.py
@@ -4,7 +4,11 @@
 
 import dags.tree as dt
 
+from ttsim.interface_dag_elements.automatically_added_functions import TIME_UNIT_LABELS
 from ttsim.interface_dag_elements.interface_node_objects import interface_function
+from ttsim.interface_dag_elements.shared import (
+    get_re_pattern_for_all_time_units_and_groupings,
+)
 from ttsim.tt_dag_elements.column_objects_param_function import PolicyInput
 from ttsim.tt_dag_elements.vectorization import scalar_type_to_array_type
 
@@ -23,8 +27,30 @@ def input_data_dtypes(
     specialized_environment__with_partialled_params_and_scalars: SpecEnvWithPartialledParamsAndScalars,  # noqa: E501
     policy_environment: PolicyEnvironment,
     tt_targets__qname: OrderedQNames,
+    labels__grouping_levels: OrderedQNames,
     labels__top_level_namespace: UnorderedQNames,
 ) -> NestedInputStructureDict:
+    """
+    A template of the required input data and their expected types.
+
+    Parameters
+    ----------
+    specialized_environment__with_partialled_params_and_scalars
+        The specialized environment with partialled parameters and scalars.
+    policy_environment
+        The policy environment containing functions and parameters.
+    tt_targets__qname
+        Ordered qualified names of the targets.
+    labels__grouping_levels
+        Ordered qualified names of grouping levels.
+    labels__top_level_namespace
+        Unordered qualified names of the top-level namespace.
+
+    Returns
+    -------
+    NestedInputStructureDict
+        A nested dictionary mapping input paths to their data types.
+    """
     base_dtype_tree = dt.create_tree_with_input_types(
         functions=dt.unflatten_from_qnames(
             specialized_environment__with_partialled_params_and_scalars,
@@ -33,18 +59,56 @@ def input_data_dtypes(
         top_level_inputs=labels__top_level_namespace,
     )
 
-    # Replace dtypes of PolicyInputs that have the generic type 'FloatColumn | IntColumn
-    # | BoolColumn' with the actual dtype found in the policy environment.
-    flat_policy_env = dt.flatten_to_tree_paths(policy_environment)
-    flat_dtype_tree = dt.flatten_to_tree_paths(base_dtype_tree)
-    out = {}
-    for p, derived_dtype_in_base in flat_dtype_tree.items():
-        policy_env_element = flat_policy_env[p]
-        if p[0] in {"evaluation_year", "evaluation_month", "evaluation_day"}:
+    qname_policy_env = dt.flatten_to_qnames(policy_environment)
+    qname_dtype_tree = dt.flatten_to_qnames(base_dtype_tree)
+    policy_inputs = {
+        k: v for k, v in qname_policy_env.items() if isinstance(v, PolicyInput)
+    }
+
+    cleaned_qname_dtype_tree: dict[str, str] = {}
+
+    pattern_all = get_re_pattern_for_all_time_units_and_groupings(
+        time_units=list(TIME_UNIT_LABELS),
+        grouping_levels=labels__grouping_levels,
+    )
+
+    for qn, derived_dtype_in_base in qname_dtype_tree.items():
+        if qn in {"evaluation_year", "evaluation_month", "evaluation_day"}:
             continue
-        if isinstance(policy_env_element, PolicyInput) and "|" in derived_dtype_in_base:
-            out[p] = scalar_type_to_array_type(policy_env_element.data_type)
+
+        match = pattern_all.fullmatch(qn)
+        base_name = match.group("base_name")
+        if (
+            base_name not in qname_dtype_tree
+            and base_name not in cleaned_qname_dtype_tree
+            and base_name in policy_inputs
+        ):
+            # If some input data is provided, we create aggregation functions
+            # automatically only if the source node is part of the input data. Hence, if
+            # the user provides incomplete input data (i.e. some policy inputs are
+            # missing) and those policy inputs are sources of automatic aggregation
+            # functions, dt.create_tree_with_input_types will return the name of the
+            # aggregation function as root node. The policy input is not in the output.
+            # We take care of this here.
+            cleaned_qname_dtype_tree[base_name] = scalar_type_to_array_type(
+                policy_inputs[base_name].data_type
+            )
+
+            # Also add the ID of the grouped variable if grouping exists
+            grouping = match.group("grouping")
+            if grouping:
+                grouping_id = f"{grouping}_id"
+                if grouping_id not in cleaned_qname_dtype_tree:
+                    cleaned_qname_dtype_tree[grouping_id] = "IntColumn"
+
+        elif qn in policy_inputs:
+            # Replace dtypes of PolicyInputs that have the generic type 'FloatColumn |
+            # IntColumn | BoolColumn' with the actual dtype found in the policy
+            # environment.
+            cleaned_qname_dtype_tree[qn] = scalar_type_to_array_type(
+                policy_inputs[qn].data_type
+            )
         else:
-            out[p] = derived_dtype_in_base
+            cleaned_qname_dtype_tree[qn] = derived_dtype_in_base
 
-    return dt.unflatten_from_tree_paths(out)
+    return dt.unflatten_from_qnames(cleaned_qname_dtype_tree)
diff --git a/tests/ttsim/interface_dag_elements/test_templates.py b/tests/ttsim/interface_dag_elements/test_templates.py
index c7b6c3acb..bb61ab488 100644
--- a/tests/ttsim/interface_dag_elements/test_templates.py
+++ b/tests/ttsim/interface_dag_elements/test_templates.py
@@ -52,6 +52,11 @@
 )
 
 
+@policy_input()
+def kin_id() -> int:
+    pass
+
+
 @policy_input()
 def inp1() -> int:
     pass
@@ -63,8 +68,8 @@ def inp2() -> float:
 
 
 @policy_function()
-def x(inp1: int, p1: int, p2: dict[str, int]) -> int:
-    return inp1 + p1 + p2["a"] + p2["b"]
+def x(inp1_kin: int, p1: int, p2: dict[str, int]) -> int:
+    return inp1_kin + p1 + p2["a"] + p2["b"]
 
 
 @policy_function()
@@ -81,6 +86,7 @@ def test_template_all_outputs_no_inputs(backend):
     actual = main(
         main_target="templates__input_data_dtypes",
         policy_environment={
+            "kin_id": kin_id,
             "inp1": inp1,
             "p1": p1,
             "a": {"inp2": inp2, "x": x, "y": y, "p2": p2},
@@ -92,7 +98,11 @@ def test_template_all_outputs_no_inputs(backend):
         evaluation_date_str="2025-01-01",
         backend=backend,
     )
-    assert actual == {"a": {"inp2": "FloatColumn"}, "inp1": "IntColumn"}
+    assert actual == {
+        "a": {"inp2": "FloatColumn"},
+        "inp1": "IntColumn",
+        "kin_id": "IntColumn",
+    }
 
 
 def test_template_all_outputs_with_inputs(backend, xnp):
@@ -108,6 +118,7 @@ def test_template_all_outputs_with_inputs(backend, xnp):
             }
         },
         policy_environment={
+            "kin_id": kin_id,
             "inp1": inp1,
             "p1": p1,
             "a": {"inp2": inp2, "x": x, "y": y, "p2": p2},
@@ -119,7 +130,11 @@ def test_template_all_outputs_with_inputs(backend, xnp):
         evaluation_date_str="2025-01-01",
         backend=backend,
     )
-    assert actual == {"a": {"inp2": "FloatColumn"}, "inp1": "IntColumn"}
+    assert actual == {
+        "a": {"inp2": "FloatColumn"},
+        "inp1": "IntColumn",
+        "kin_id": "IntColumn",
+    }
 
 
 def test_template_output_y_no_inputs(backend):
@@ -127,6 +142,7 @@ def test_template_output_y_no_inputs(backend):
         main_target="templates__input_data_dtypes",
         tt_targets={"tree": {"a": {"y": None}}},
         policy_environment={
+            "kin_id": kin_id,
             "inp1": inp1,
             "p1": p1,
             "a": {"inp2": inp2, "x": x, "y": y, "p2": p2},
@@ -155,6 +171,34 @@ def test_template_output_x_with_inputs(backend, xnp):
         },
         tt_targets={"tree": {"a": {"x": None}}},
         policy_environment={
+            "kin_id": kin_id,
+            "inp1": inp1,
+            "p1": p1,
+            "a": {"inp2": inp2, "x": x, "y": y, "p2": p2},
+            "b": {
+                "z": z,
+            },
+        },
+        rounding=True,
+        evaluation_date_str="2025-01-01",
+        backend=backend,
+    )
+    assert actual == {"inp1": "IntColumn", "kin_id": "IntColumn"}
+
+
+def test_template_all_outputs_no_input_for_root_of_derived_function(backend, xnp):
+    actual = main(
+        main_target="templates__input_data_dtypes",
+        input_data={
+            "tree": {
+                "p_id": xnp.array([4, 5, 6]),
+                "a": {
+                    "inp2": xnp.array([1, 2, 3]),
+                },
+            }
+        },
+        policy_environment={
+            "kin_id": kin_id,
             "inp1": inp1,
             "p1": p1,
             "a": {"inp2": inp2, "x": x, "y": y, "p2": p2},
@@ -166,4 +210,8 @@ def test_template_output_x_with_inputs(backend, xnp):
         evaluation_date_str="2025-01-01",
         backend=backend,
     )
-    assert actual == {"inp1": "IntColumn"}
+    assert actual == {
+        "a": {"inp2": "FloatColumn"},
+        "inp1": "IntColumn",
+        "kin_id": "IntColumn",
+    }